Yeah, 'teke's stream compilation is very good for that, atleast it was for me. Once you can handle almost all the streams there, move on to chipscape or something. Also I found out that I stream much better using wider key positions, c and s for me, instead of z and x.
I tried using different finger combinations. I noticed my index and ring finger could keep a more consistant streaming speed, but it felt weird, and was a bit slower when compared to using my index and middle finger.
I also tried different keys. I used to use ZX a lot, then switched to SD, then kinda went all over the keyboard going to 56, GH, Spacebar and Alt, etc... I'm back to ZX now.
I now just usually do some insane streaming practice right before going to bed.
With streaming, idk if I'm really consitant with it or not. Like there is times where I'll hit every stream perfectly in a song, then there are times where I can't even do the first stream on that same song. I guess I need to work on timing? Idk. Usually when I see a bunch of beat's right on top of each other, I don't count how many beats are there or anything, I just sort of spam Z and X. I guess it works out...
As for individual finger speed, my index and middle finger on my right hand are noticeably faster then the index and middle on my left hand. Problem is, I can't seem to do any mouse clicking at all without loosing accuracy :/
play my stream compilation until you can at least pass it
This. Or just practice on Mei, Shinsekai (not aho's version), or DT some streamy maps. When you stream, I find it better to stream with the keyboard only, as you can focus on the rhythm for your left hand (assuming you're right-handed) and just move with your right one.
This will of course lead to imbalances in your two hands' accuracies and stream hitting speed.
much better training than any osu map, especially because you can slow it down and speed it up .5-1.5x
but if you insist, play maps on half time and practice using 2 fingers until you know the rhythm of the song, then do it full size. Play maps that you know you can stream properly then increase the BPM slightly and play a map of similar bpm.