Oh, and as far as specific techniques: experiment, watch other climbers, ask other climbers, ask for feedback. If you are toproping, you can play around for as long as you'd like and start to learn what works/doesn't work. If you can find someone who is better at these problems than you are, you can both work on the same roof and a little informal coaching can take place. The No Picnic roof would be well suited for this.
Each situation is different, but as a general rule you don't want to start getting contemplative and introspective in the middle of an overhang. The typical 'Gunks roof requires an aggressive, assertive approach.

Roofs? Easy. Climb at a tall overhanging gym. Get someone better at it to watch. Climb outside at the Gunks! Yes, what Dana and everyone esle has said.

You want the confidence to do it and exact knowlege of how hard you can push yourself while doing it. As in any climbing, mental insecurity can shut you down very quickly. As RG wrote hand strength is important. Really, for fast progress find someone who understands movement and climbing to watch you and advise.

I agree with most of the points made above and would add core strength to the list.

If you toprope/follow enough roofs at a similar grade, you'll probably get a good sense of what you are capable of, which will lead to you feeling confident and, importantly, relaxed, when on lead. There are a lot of roofs you can TR even if you are the only leader in your party, especially if you are willing to be lowered down from a top anchor.

Abs-olutely! As in all things physical, core is paramount. Nothing more frustrating on a big body length roof then to be up in there tight reaching for the lip then to have your core give out and your ass start sagging and heading towards the ground a few moments before the rest of your body.

Core strenght yes. Actually because you are tall this will be more of an issue for you than compact people like me. You can do sonme exercises to suplement, but the best way to accomplish this is climbing overhanging stuff. That generally means relativley juggy. For me this is far more easily done in a great gym.

Top rope. Never been a promoter of top roping longer than you need to, You don't learn the attictude or positions you need to have in muscle memory for clipping or placing gear TR. Far to easy to just go for it and get shut down anyway when on lead.

I'm non small. Core strength. Down climbing. HEEL HOOKING. Core strength. Do figure 4 / 9 in the gym. Use your extreme reach rather than suffer from it. Follow / TR. What works for us non small folks is not what works for dinkys. Forget about them, and TR or follow the piss out of something(s) hard until you develop the bizarre kinesthetics required for leading roofs when you're too tall for some of them.

MF is really hard when you're tall, and NEVER go near PT Phone Home.

Good luck!

Haven't these techniques or skills proven effective for climbers of all sizes?

It seems to be a rule of climbing that people, whether they are relatively tall or short, will construe their height to be a disadvantage.

And, see the advantage of the other. Being of average height has always been a challenge for me where as those shorter or taller, have always had it easier.

it's all about a strong core