Tip #1: Don't cosplaying without planning!
If you just start buying a bunch of pieces of your cosplay without planning at all, you're going to end up either: A) spending way more than you want to orB) not being satisfied with the results I know, I know...it can sound tiresome to have to plan, but you'll be much happier with the results if you plan out what you're going to do ahead of time, even if its just some basic planning :D
Tip #2: Take pictures!
Look, you don't have to get anything too official taken. But make sure you take at least 10 or 20 pictures in your cosplay!! You'll end up regretting it later if you don't. Smart phone cameras are good enough to take these pictures, you know!! So no excuses :P
You can also look up cosplay photographers who will be doing free shoots (there are some just trying to practice their art) and try to set up a time with them! Or just ask a friend with a camera.
However you do it, just get some pictures!
And that's it for now!
Hope those tips help you :)