Look at the characters you like and enjoy. It's not necessarily about being the right height or weight or perfect matching body, but having fun doing it. Some people will disagree, others have their own opinions. I think it's about making the effort and having a good time doing so.
Look at the shows you like! Look at what other people have done that make you go "ooh" and "aaah." If you like getting the attention of being an uncommon character, look at your favorite shows and choose a minor character, a supporting role.
If you're a beginner, start with something simple that may take more purchases and less straight-up stitching! There are plenty of characters who wear relatively common outfits that only need minor adjustments/additives and are pretty fun to cosplay as.
If you're really concerned about that accuracy thing to your height or shape, I couldn't be of much use. Some of the best cosplay I have seen is on a person far larger than the typical slender character of a show. <3 Corsetted characters can help change your size, and height doesn't necessarily have to mean you're short! 5'2" in a pair of 2" heels is now 5'4"! Plus, the outfit can also make the difference. There is a lot of proportioning and shape happening in many silhouettes that can change a person's look just by tricking the eye.
I hope you have fun, and I hope this was able to help in some way! I know I'm a little repetitive, buuuut I like to make sure people get my point!