I normally use an anchor. I usually count my breaths and after a while I start to drift off, lose count, and pick from the last number I remember. Most times I get to a point where I feel my limbs tingling and occasionally they have twitches.

Also, I'm not sure if I've gotten to the hypnagogic stage. I've never seen colours nor shapes appear. After a while, I just see black or blackish-grey stuff moving; they basically blend in with the back of my eyes. I'm not sure if that was hypnagogic imagery.