They're tricky little boogers but it does get easier with more practice. Worry about 2 needles at a time and figure the other(s) as stitch holders. To prevent loose stitches at the ends, either make those stitches tighter or move them around. That is, when you get to the end of a needle, knit the first one or two on the next needle before switching needles. That way it at least avoids the stretch in the same column of stitches.