Playing with a pick

I'm a self-taught bassist and I guess I can still be considered a beginner, especially when it comes to playing with a pick. I play mostly with fingers but I recently decided to start learning Love Will Tear Us Apart by Joy Division and I noticed that I had a lot of trouble keeping my sound consistent on all strings, and to not make it sound like desperate hits when you strike multiple strings together. I also know a little bit how to play (electric) guitar but since those strings are way closer together and much thinner I've never had much difficulty striking multiple strings on guitar.

Does anybody know any tips for getting a good pick technique and a nice consistent sound? (also interested in hearing what thickness your picks are)