In RW flight you are contstantly adjusting your trim. The AP (Autopilot) takes a lot of this on, but, depending on the aircraft, this could be a contstant challenge. If you have your settings to ultra real (thermals, winds, etc.) you will contantly have to adjust this. This is just part and parcel for flying. The conditions are always changing, so the trim of your aircraft is always changing. Trim in the RW is meant to take the load off of the pilot by relieving the pressure on the yoke that has to be applied to compensate for the constant changing variables. The idea is to find that happy medium while you are in different stages of flight. Just remember that any change to power, pitch or bank will likely require a change in trim.
The answer to your question is two fold. If you are using AP, the AP should be adjusting this to maintain straight and level flight, or to maintain altitude while banking. The second part of this requires a little more information about what conditions you are flying in (straight and level, banking, ascent, descent, high/low power, etc.). These all effect trim and its ultimate goal, which is to take the pressure the pilot has to exert off of the yoke as much as possible.
If I had a little more information from you I think I could give you an answer that would better fit.