Gradual rise in throttle is very good advice. You need to use your rudder until just before lift off and then start transitioning to ailerons to control the roll as it lifts off the ground. At least this is what solved my problem. I had this problem with a trainer and I found that I wasn't transitioning properly from ground control (rudder and throttle) to air control (aileron and throttle). The rudder control and aileron have to overlap a little on takeoff, especially in a cross wind.

I don't miss trainers for this reason.

Joe