I like to think I'm fairly good, at least. I'm certainly no top-level player, but I've cleared every Extra stage and can 1cc about half of the games on Lunatic.
As for tips...
- The best one I can give is simply to keep playing and enjoy the game. I started playing Touhou (and shmups in general) almost 8 years ago now; there isn't a person alive that doesn't completely suck when they first start playing.
- If you greatly suspect you're about to die, don't be afraid to use a bomb. Your bomb stock will be replenished to 2-4 when you die (depending on character/game), so excess stock is wasted if you don't use them up.
- Learn to 'stream' bullets early, as you'll be doing it a lot in virtually every Touhou game. You can do this by simply moving slowly in one direction when streams of bullets are aimed at you continuously (the beginning of PCB's extra/phantasm stage is a good example of where this is useful, and a good place to practice).
- New players tend to hold focus almost constantly; don't be afraid to unfocus to quickly avoid being trapped.
- Some players advocate intentionally playing on a higher difficulty level than is 'suited to you' in order to get better at the games faster, although I'm unsure how much merit there really is to this. That being said, I moved onto Extra stages after Normal myself, which was a great struggle at the time. I wouldn't jump so far ahead that you're getting completely stomped on Stage 1 or 2, though.
- Virtually every method of control (keyboard, controller, arcade stick, etc) has top-level player representation. Feel free to experiment with a different control scheme to see if it works better for you- it's better to try this early on anyway, before you become too accustomed to the original scheme you were using.
- If you're really stuck, you can watch replays of a particular stage or spell. Be wary of watching replays of stages or spells you haven't seen yet, however, as experiencing them 'blind' for yourself is generally more entertaining.