I get how daunting it can be, I remember around 2013 I was invited to go to a convention with some friends and wasn’t even sure what cosplay was at the time, I ended up deciding to cosplay a young Erza Scarlet from Fairy Tail, as I was a big fan at the time, my mum made her dress, I created her sword and shield out or cardboard, duct tape with paint and then bought her wig and eyepatch online.
To start there are a few things to think about; are there any characters that you love or something that you are into recently? For example, an anime series, Warhammer, a video game, etc. What type of cosplay would you like to do? Do you have the skills/resources to achieve this? How simple is the design? Can you afford this? Would you need to wear contact lenses? Are there any existing tutorials for cosplaying the character? Would you feel comfortable cosplaying this character? Can you practice styling wigs?