Advice for bass line construction

[TheNightman]

Hey everyone, I'm new to the thread and have recently hit a plateau in putting together bass lines. I play with two bands and only recently in one of them have I started to put together bass lines responsively. That is, for a while I've been putting together the songs and only recently has everyone else been writing (which I am in full support of).
In the other band, a good friend of mine writes all the songs. Since we do not have the time during the year to jam a lot, I just jump in right before recording and put together almost anything I want. The songs are much simpler and I have a lot more freedom.
My issue is that in the band which I play with very often has much more difficult music. There are a lot of weird times (I have no problem writing in odd times, just writing to someone else's music that has them) and more strange keys that are used.
I was wondering if anyone could give me some advice as to writing more independent bass lines. I've been playing for about four years and I don't know any theory, so I was hoping I could get some advice as to different approaches towards differentiating my bass lines more while still maintaining the feel of what I'm writing to.
The last thing my band did is on bandcamp: capitalh.bandcamp.com
Any advice would be great. I imagine this is something a lot of bassists have had issues with and because I don't know many other bass players I was hoping someone could give me some tips.

[DanNowhere]

Advice from the unschooled, non-theory feel player (me):

If the song's pretty complex, I try to keep the bass line as simple as I can and find my space in there somewhere. If I try to do too much, it turns into noodle soup.

Not sure how helpful that is, but keeping it simple and sparse at first is my rule of thumb. As the song gels, then I elaborate on it. I don't sit down and write a line so much as just let it evolve over time.

[fearceol]

If you can get a recording of the bare bones of the music to be played. Then sit down without your bass and sing or hum a bass line to what is being played. Then play what you just sang.