hey there! looks like you've started the first steps already tbh! scrolling through rp side of tumblr and finding active blogs to follow is a great start. you can make little promos for yourself too that act as a sort of advertisement to other rpers that basically says 'hey, i rp! follow me maybe?' which can be decorated however you'd like. i'm sure you've seen a couple around already depending on the tags you were searching.
you can check out my tag here to find a whole list of people's promos they have made for a better visual on what you might want to do if you're a visual type of learner. i try my best to reblog as many as i see, so there should be a big mix of different writers in there that might help you gain some more writing partners!
reading people's rules when you do follow them is a good habit to make too as some are considered 'mutuals only' and other similar terms where they will only rp with people they follow back and so on. sometimes that involves age, where certain peeps will only interact with other individuals closer to their own age/etc. most of the time it's due to comfort reasons.
making 'open starters' for others to respond to is another good way to start! typically those are posts that allow other people that follow you to respond with their own characters if they'd like. you can also send in prompts/asks to others' inboxes as your character for people to consider writing to as well. reaching out ooc in the same manner asking if they'd like to rp might also help!
i've probably missed a lot, but i know there's a TON of people around that are more than willing to add to this to help you out with getting started! thanks for asking me for help and happy hunting, fellow roleplayer! <3
