I spent an hour mining silver ore at Quarrymill, quick synthesised it all into ingots on my GLD (at 400XP per turn), then bought a stack of Glass Lenses and started banging out Silver Magnifiers for 3k XP per HQ synth (first synthesising Silver Spectacles) and turning the HQ Mags in for the Ul'dah Levequest All Booked Up
, Turning in 9 HQ items will net you 99k XP. So long as you take your time (crafting is a bit of a game) you'll reap the rewards. I went from 26-30 in an evening.
Best advice I can give to anyone crafting is level Alchamist to 15 first so you get the Tricks of the Trade ability, it's a Godsend. Whenever the item quality changes to good you can use this ability to regain 20CP.
Selling the NQ items back on the Market Wards and the gil rewards from the levequest put me into profit also.