Well done for seeing the light, OP!
It is tricky and anxiety-inducing to stop people pleasing. Why don't you start with something like, if someone asks you if you'd mind doing a really long/boring/nasty task, saying, "I'm very sorry, I'm afraid that I can't as I'm doing X". That way, you're getting out of things, but you are still being polite!
Then work on thinking more for yourself, and doing things that please you. This might mean going to the pictures on your own, because nobody else wants to see the same film, but give it a go.
Then practice saying, "No" to anything that you definitely disagree with, instead of, "I'll go with the majority..."
Also, if people don't do things for you (e.g. replacing the empty loo roll, or eat everything of yours from the fridge, or leaving things empty and putting them back), don't do it for them.
Enjoy!