I'd mostly be echoing what people said here, but I did want to point out that pretty much every class has a useful skill at lvl 15 that can be used as cross-class, so if you plan to level your crafters, it helps to get as much to 15 as you can early on for those cross class skills. The WVR cross class skills at 15 and 50 are probably the most useful for Leveling, followed by the GSM 15 skill, so I'd knock out a bit of weaving too when you get a moment (it's right near GSM guild in uldah).