I've been searching for games to speedrun for a while, and the only thing I think I'm able of running again and again is the first Dark Souls, I haven't played it, I've gone through almost the whole second game and finished the third twice, I thought I should finish the first game regularly twice and then slowly start learning speedrunning methods for the game. Any tips or recommendations?

Don't speedrun a game that you've never played before. It won't do well for you. Definitely if you're thinking of DS 1 then play through it once or twice. And then slowly start learning the strats (like you said).

i started off playing nes games, you can speedrun heaps old school games in 10 mins or less. which is a good start. keep it simple to start with