Advice for a new cosplayer and my character’s costumes

hey gang! I’ve never cosplayed ir really dressed up (only Halloween 😔😔). I’m going to my first ever comic con in september, and I’m trying to slowly gather parts for my costume as I cant buy it all at once.

So I have like no clue what I’m doing! and I’d love some advice. Whatever shops you guys go to I’d love to hear about. Currently I’ve been looking at Temu (😔) and Depop. I have not ordered anything yet but I’m just looking. Where should I look?

I’d also love advice on the characters I’m dressing up as. I’m going to be Twilight Sparkle from My Little Pony, and Evangeline Fox from Once Upon A Broken Heart. Evangeline isn’t very known but if anyone has ideas or suggestions for either of the characters I’d love to get some.

Is there anything else I should know abt cosplay? because I’m super duper excited and want to do it right.