I admire the hell out of you guys that have your professions maxed or high up there, or even just high-ish for your lvl. I have been finding out how hard it is.. and expensive. My respects.
GATHER GATHER!
One thing I read about profession leveling that stuck with me is don't even try to level non-gathering professions like Alchemy, Engineering etc until after 50-60 when you have already earned enough gold from gathering profs that you have your mount, flight mount, dual spec etc, and can afford to purchase most of the stuffs you need.
Also, try and make sure that the recipes you get for your profs are worth more on AH than what it would cost you (or lose you) in material sales to make them.
ANALYZE:
Write it down. What does that jewelled chest piece cost you to make? 3xthingamabobs (that take 4x these and 3xthose and 2 of those rare things each) plus 4 of these special things (that take 3 of those, plus 2 of these and one of those) and 2 each of those and those, ... add it all up right from base materials, what it exactly costs to make.. and then what can you get from it on the AH. Most things are a losing sale. Find ones that make you cash, search AH for things that sell high, make those if the production cost is worth it.
If you are at the point where you have a ton of gold spare, and your guild needs the skill, or you need the special sets for your character, or you just want to have fun with it, then fine.
If not, gather profs until you are bored and rich. Then specialize.
Leveling most crafting professions is hugely expensive. That is how the AH'ers make the big bucks. --> On supplying levelers.
I am going to give myself a break until I am higher and can afford it before I start hitting mine hard. Until then, I will pay the higher up pros who have gone through it. They deserve my gold. (Yes, I know a lot of things are way over priced.... supply and demand, right?) Unless of course you are a guildie and I can get it free.
(you guys know that if you need anything, I will give it to you, right? right??)