Responces here are good example of different strokes for different folks. EDIT! It occurred to me I should mention how easy it is to knock the ring on 180° wrong while looking at backside of wheel. Look twice
I use a good quality pair of snap ring spreaders.....like the ones used in transmission overhauls. Just keep your hand on it while spreading! Those spreaders like to slip off and that cancel piece can spring out and do some serious damage. Once you get it started, you can tap it down into place with punch.