Hardest problem I'm running into is I want to get into over detailing what are only basic troop models. It includes wanting to try to hit tiny bits that can only be seen when you turn the model over, hold it a particular angle, use a bright light and magnifier. When the downside is making a clear "oopsie" if the brush slips even a little. Fortunately I almost "oopsied" real badly, but it was small enough and I was quick enough to get a damp brush in there and wipe it off.
Another mental trick I'm using is promising to do stuff I want a bit of detail painting along with each major color run through so that I do get some tiny variation between models.