On my MKIII .60 size trainer that comes with the OS .65LA engine I usually fly 1/2 throttle ... This is more than enough to fly the regular field pattern circle (without using any rolls or loops ... I am still a beginner) ...

On my 60 size Protege with the MDS engine, I am flying 1/4 throttle ... There is a region in that engine from 1/4<->3/4 where the plane tends to have issues... the engine wants to stop ... (not to hijack the thread with problems ...)

So in other words, my style of flying is slow ... so I trim with the throttle low as others have suggested.

I found out that after doing the initial trim, IFyou change the throttle position at all, you have to go through another trimming exercise. Its very difficult to go back to the original throttle position if you shift.

Play around with the throttle and don't be scared to reduce/increase its settings while you are flying ...

I like to fly high and then slow the plane (trainer) as much as I can so I can get used to almost stalling speed. You never know when it may come handy.