Couple good ways to do it, really.
If getting to 60 as fast as possible is your goal, then just doing them later is what you want to do. Because even leveling gathering as you go, to keep them up with you will slow you down a tad.
If you aren't in a great rush, but want to pull in some gold on the way? Leveling gathering as you go is the best bet. Then switch to long term plans for professions 50+ or 60, or whatnot.