In a nutshell: Being smaller might feel like a handicap... but if your goal isn't just to fly, but to get GOOD at it, being small is a huge advantage!
When you're smaller, you have less ability- probably strength too but definitely less leverage- to "muscle" the glider around. That applies to both ground handling and in-flight inputs. Instead, you will have to learn and refine your technique, and your timing. Hang gliding is absolutely a finesse activity, and so when people complain about how hard they were working to turn a glider or how tired their arms are after a flight... you can laugh at them because they are admitting- without even knowing it- that their flying is very unrefined. Smaller pilots don't have that option, so you will learn by default the better way of doing things.
Since all of that is speaking in generalities more than specifics, here are a couple specific things:
1) Launching- This is the same for everyone, but smaller pilots are usually LIGHTER pilots, too- and this becomes a "thing" when launching... especially when there's some wind. The solution is the same thing pilots of all sizes should be doing anyway- solid PITCH control. A heavier, stronger pilot can usually pull DOWN on the downtubes... which applies weight forward of the hang point and therefore tells the glider to fly faster. Because the heavier pilot is heavier, this tighter gripped pulling down thing can work. Doesn't make it right... but it works... and they might not know they are doing it, nor are they "forced" to learn doing it a better way, 'cause they can get the result they want that way (although it has drawbacks and weaknesses that increase risk and decrease effective control, but I won't go into that here). What YOU want to do is remember that you're launching a WEIGHT SHIFT controlled aircraft, and so if you don't want to get picked up early, you want to pull *IN*. That is, if you're standing in the upright position, you want to pull your hands back toward your hips. Or toward the end of the keel if you prefer that visualization. This can (and should) be done with a very LOOSE grip, allowing you to feel the glider, and feel the pitch pressure feedback telling you how much airspeed you've built up.
A quick side story, flying a ridge soaring mountain side in the Crawford Mountains in Randolph, UT... it was kinda strong, on the edge of what we would fly in vs calling it blown out. My wife, who's all of 110 lbs at the most (and I doubt that) stands on launch, says clear, and she powers off taking easily two more steps than any other pilot took that day. The pilots still on launch were jaw-dropped speechless. They couldn't understand- like literally did not get- how she was able to do that. They were stuck on the fact that it was blowing in so hard, and she's so light, why wasn't she just picked up right away?! The answer is simple... pitch control. She was pulling in, telling the glider to fly faster, allowing her to not just keep her feet on the ground, but also accelerate forward into the strong headwind. It was awesome, and the other pilot's reactions really stood out in my mind how they probably hadn't learned this more technical (more correct) way of launching, where pilot weight is not relevant as long as they're not on a massive tandem glider or something crazy.
2) Thermalling- when climbing in a thermal there's usually a bunch of inputs needed. If you can get really nicely centered, in a really nice thermal that doesn't snake around, maybe you can do little or even no adjusting... and that's always the objective... but in reality climbing usually involves lots of re-centering and trying to always find and stay in the lift/core. Learn to feel what the glider is doing while you climb. There are times where a roll input will be quickly effective, and there are times where the glider will be resistant and feel sluggish- which is when bigger pilots just input harder until they get what they wanted. Instead, try to recognize if it's not a good moment for that input... pause for just a half second or something- assuming you're not near terrain or other gliders and the input we're talking about is with regard to thermalling and not survival LOL- and then try again. Usually you'll find the glider to be much more responsive. I believe this is due to the fact that our gliders are constantly yawing about, usually subtly enough that we don't really notice, but it's still happening just the same. With roll inputs comes adverse yaw, so an input for a right turn would yaw the nose to the left. If the glider was currently yawing slightly to the right, your right-roll input is going to be met with resistance from the inertia/momentum of the yaw. Waiting just a moment the nose will probably then be yawing ever so slightly back the other way, and now your roll input is complimented by that movement. If you maintain a light grip and try to really feel the glider, after a while you will intuitively "know" the times to add your input, and when to wait a moment because it won't do much just then. You'll learn to do this without even thinking about it... so it's not like you will always be needing to thing about when and when not to give inputs. And again, this is something many pilots will never learn... because they don't *HAVE* to, they instead just push harder to throw their weight around more, and tire out their arms more.
3) You mentioned flare authority. Do *not* listen to people parroting the age-old "wisdom" to slide your hands up higher. It's a falsehood! It sounds good, and enough people have said it enough times that it's stuck around since the dark ages of hang gliding... but it's malarkey! Your flare authority is defined by how much weight you can move and how far aft you can move it. The flare is a weight shift input like everything else. If you slide your hands up the down tubes, you actually end up straightening your arms (elbows). Bent elbows are like a loaded slingshot ready to fire... you've got lots of flare at your disposal. Straight elbows and hands up... you're like half-uncocked already. Not to mention the leverage/mechanical advantage loss of having your arms straighter and hands higher... to push your weight aft in that position requires a lot of shoulder strength, and it's using a muscle we don't use often in everyday life. Instead, keep your hands about shoulder height when you get upright. Now, if "shoulder height" can be higher, then yes absolutely that will increase your flare authority! Shoulder height gets higher by getting more upright. But pulling yourself upright doesn't count- it's a matter of your harness and how it hangs you. A well fitting harness in very important for everyone, but I would say more so for smaller pilots. Also, some styles of harness tend to get the pilot into a more upright body position than others... so you might consider that in your equipment selections.
4) When you do flare, strive to do what I like to call a "quarter-loop" flare, where the glider climbs just a tiny bit as the nose rotates up. Doing this is transferring airspeed- forward momentum- into altitude for just a moment, and it's the secret to stopping! Doing this transfer of energy means the flare can and should be a slow and smooth motion, not an abrubt or sharp shove out. You want to shift your weight aft, and let the glider respond by pitching up into a climbing stall. Again this technique could be described as finesse rather than muscling the glider to a stop by shoving the nose up with an abrupt flare. It works great for some, but not for little pilots. Not for a lot of pilots, actually... The other great thing about the "quarter loop flare" is that it all happens slower, giving the pilot a chance to process and adjust as necessary. What you're going for is just that little bit of climb, and a slow smooth flare motion... so if you start your flare and climb a lot, or very quickly, stop pushing out any more until the climbing stops, and THEN finish the flare. And if you start your smooth flare and the glider doesn't climb much or at all, now you know you're a tad late and you can speed up your flare motion (and expect to run). Think of the flare as a balance of two elements, the timing and the technique. If you're early or late, adjust the technique (the rate of your flare motion) to compensate and balance things out for a perfect flare again. When you get good at this, size doesn't matter... and while every landing might feel a little different to you, the pilot, because we're always ballparking the flare timing, but now you're adjusting the flare rate accordingly... but to the crowd watching, it leads to what appears to be the same exact landing time after time after time. Because you're keeping the flare equation- made up of those two elements- balanced... you know this one was more A and less B, and that other landing was more B but not so much A... but all people see is the sum, the result. This might not be a little-pilot specific thing... except that doing it some of the other ways that OTHER people (like people with long gorilla arms) do it probably won't work so well for you.
Hope that helps! Sorry it's a lot to take in... I might have got carried away...
Shut up and fly.