Watch your water params... they will tell you everything. The goal is to keep ammonia and nitrite at 0 and nitrate under 40 (under 20 is safer).
Usually once/wk should be enough, change about 25 -30% each week, don't overfeed and keep up maintenance on your filter. If you have a skimmer running and enough live rock in there you may notice you can get away with a water change once every 2 - 3 wks, but also watch your spg/salinity when doing any freshwater top offs in between. Water evaporates, waste and salt do not. Evaporation will cause waste and salt levels to fluctuate, so the regular water changes should help to keep those safely under control.