lol I know exactly what you mean.
The problem with making your first mission is that there is so much learn, and its all inter-related. I found a useful technique was to d/l a random tutorial from time to time and just skim read it. It gives you an insight into the possible, and when you run up against a problem it gives you a chance of saying, hang on, didn't I read a tute abou that?
So, design a bit, read a bit, design a bit, dig through OFPEC to solve a particular problem, design a bit, read a bit etc etc. You've got to mix it up.
Everything you need to know for a decent basic mission (except choppers ;D ) is in the Tutorial Mission, so it really is worth getting to know it. Play it in the Editor a couple of times ... did you know that when you are playing in the Editor, you can exit the game back to the Editor Map, have a look around, even change things, and then go back into your game just where you left off by pressing Continue? The changes don't take effect till you hit save or preview. Means you can be playing through the mission, think "I wonder how he did that?", go out to the mission editor screen and check it out, then continue the mission.