keep trying, keep practicing!
I often hear complaints of people saying "I tried to do the flared eyeliner thing but it didn't work." Or you could insert any technique... this was but an example. Having tried it once is not an indicator of whether you will succeed or not with that technique in general. Some techniques do take a whole lot of time to get right. For example, I think that it took me no less than a month to get the hang of applying liquid eyeliner in a way that looked good... and then it must have taken me another few months to be able to apply in a consistent manner. Now there may be techniques that you get at the first try. It happens.
Often we feel fear when it comes to trying something new in general and this is no less true for a new makeup technique. You wish that you'll get it right away but it may or may not happen. That fear can hold you back from even trying... which is sad (and that goes for everything... not just makeup :p). But in the case of makeup, what's the worst that can happen? You need to redo the makeup or correct it. That's about it. No one's dying. Heck, no one has to see it!
So, really, when you're trying something new, you have to fight old patterns. By that I mean that you may have ingrained in you some way of applying the makeup and you will have to fight that to try the new technique. For example, you are used to flaring out the eye shadow at the crease into a pointy triangle but you're trying to do a more rounded shape... you'll have to resist the urge to point it up and strive to keep it rounded. It can be hard. I know. I've had to fight those patterns. ;)
Failure is not necessarily bad
So you haven't achieved the look that you were hoping to get. Well, maybe you still like the look! If so, make a mental note... you can redo it. If you don't, before you quickly remove the makeup, assess what could possibly have gone wrong. Where do you think you have erred? This is important so as not to repeat the same mistake.
It takes time
So, as mentioned above regarding liquid liner application, some techniques just plain take time to get the hang of. So don't feel like you're a failure for not having been able to do it right away. Just keep at it. It's just like practicing any other thing: you need to do it multiple times before you can do it consistently.