I see a very common thing online with people who are new to crossplay (either being existing cosplayers or complete newbies) approaching it COMPLETELY wrong. This post is mostly about males cosplaying female characters, but the same advice applies either way.
The question that I see most often that perfectly sums up this problem is "how do I pass?". I've made posts before about crossdressing and crossplay and why passing is completely not the right way to think, but here's another one, I guess.
To me, cosplay is about expressing yourself and your love of a character or series, having fun, and getting to wear cool things you wouldn't otherwise be able to, and crossplay isn't some dark art, or some weird thing, it's still just cosplay.
Approaching crossplay with the intent of passing or a focus on passing is completely the wrong way to think. Start by finding a character you love, an outfit you want to wear, or something that would be fun to make (if you make your own costumes). Find a cosplay you're passionate about. Then, get the costume (either make or buy, I always recommend making your own if you can) and congrats, you're crossplaying, enjoy it. It's that easy.
You may notice I never mentioned contouring, false breasts, padding, or anything like that. That's because those things are not important. I'm not saying those things are bad, if they'd make you happier. Feel like doing drag makeup? Sure, why not. Would you be happier with boobs or other ways to try and look "more female"? Then go for it. But things like that are, really, not important.
Cosplay is about enjoying yourself, not trying to deceive other people. If passing is what would make you happiest and you'd have most fun doing, then go for it. But it isn't what crossplay is about, and you should focus on having fun rather than trying to look female. Crossplaying is just cosplaying, so just do the same as you would for any cosplay. Passing isn't required. Hell, it isn't even encouraged.
Don't come into crossplaying asking how to pass. Come into crossplaying asking how to have fun and follow what you love.