I don't, I never want to go back to the crusts. The only way I know to stop them coming is to be tactical about it.
If you leave them alone, the crusts WILL build up. That is a fact.
I used to smother them in vaseline in the past and this caused them to peel very easily, so I would tactically do this to prevent build up.
Now with aquaphor I don't really need to be tactical, it's just what I apply all the time and I don't have to worry about thick crusts or build up. I haven't actually had any in a long time.
If I can't apply anything for a while (e.g if I go out for the night and am too drunk to care) my lips will begin to build and harden up. As soon as I am back into my senses I'll apply aquaphor again and they'll soften up and eventually peel within a day or two. Comfortably too, no excess force required.