Assuming you have point and not a Boyer or Lucas Rita, find top dead center (TDC) by removing the spark plugs and using a wood dowel (pencil?) carefully turn the back wheel while in 4th until the pencil stops rising and begins to fall. Take off the intake and exhaust rocker covers. Rattle the rockers. One side will be loose (within clearances) meaning both intake and exhaust valves are closed. This is the cylinder on compression. Back the cylinder to about 26 degrees and carefully bump it to 28 (forward). Follow the ignition lead to the coil and note what color the low voltage wires are (white/black or yellow/black). The corresponding color in the points housing tells you which set of points to use. Rotate the advance mechanism to full advance and lock it with the stepped washer before moving the points plate.
Rotate the engine 360 degrees and set the other side.
Remove the advance lock, replace the valve covers. Check the settings with a timing light.
Better yet, get a Boyer or Rita, set it and forget it.
Ron L