When I play bass i tend to hum the line inside my head. My drummer says that he counts the beats in his head, you know one and two an three and four etc and he plays away. I think that is would be quite beneficial for timing if i were to do this but when i try i seem to slip back into humming away or screwing up the line i tend to go more on the feel of things. not a bad approach probably but also probably not very pragmatic. Just curious what you other musicianers do.