4/4 FTW.
What I found useful, and to be honest I now do it unconsciously, was to count 1,2,3,4,1,2,3,4... and so on whilst I was listening to a song and feel myself fit into the rythm. Once you've done that try combining it with tapping your feet and/or your hands/fingers.
Pretty soon you'll find that you do it unconsciously.
You don't necessarily need to be using your bass to practice your rythm, it's not dependant on the instrument, only you really.
make sure that you pick something obvious to count to - hat, snare, kick. If there is a silent bit or a long intro, try counting in or counting through so that the rythm comes in on the right beat.