Alchemy

In alchemy you can have three specs flask,elixir and transmute. For each spec when you craft you specialty, you have a chance to proc 1-5 extra of what ever item you are crafting.I would recommend when you are gone choose one take transmute because it's the easiest one to get then you can pay to respec to any other of the specs. You learn the specs from this guy http://www.wowhead.com/npc=22427.
Lauranna Thar'well - Cenerarion Refuge in Zangarmarsh(Potions Master)
Zarevhi - Stormspire in Netherstorm (Transmutes Master)
Lorokeem - Shattrath Lower City in Terrokar (Elixers Master)

Transmute
With transmute you can transmute one epic gem every day, transmute is good for a steady income, this is be increased if you have a jewel crafter to cut you gem. always check what mats to profit are the highest and transmute that one. You will have a chance on procing 1-5 extra gems when you transmute for the same mats cost. You can also craft earthsiege and skyflare meta gems, which if you have a jewelcrafter you can get a good profit from.

Good: a steady sure income, chance of extra gems.
Bad: hard to increase your income.

Flask/elixir mastery
With flask spec you have a chance to proc 4-10 flask,I am myself not into the flask business but i have heard that you can make a good amount of gold from it. You can be in the flask market without having flask spec but on server that have hard competition and the profit is very low, you will need flask spec to be able to make a profit. this is how popular the different flasks are


Flask of Endless Rage - 5
Flask of Stoneblood - 3
Flask of Pure mojo - 2
Flask of the frost wyrm - 5
Potion of speed - 5
Potion of wild magic - 4.5-5
Endless mana potion - 2
Endless health potion - 2

The numbers represent which sell better then others. 1 being non existant and 5 being can't keep in stock. This of course varies with server and all that jazz but the general trend follows. Endless rage and frost wyrm are what all the dps in the game use and most healers use frost wyrm as well. Stoneblood is an alright seller but not nearly as well simply because there are more dps in a raid then tanks.

And here is the price cycle
Tuesday and Wednesday are the nights prices spike. By Saturday most of the raiding guilds have finished or are finishing up. Prices tend to fall Sunday night / Monday morning. Depending on the Pug status of your server Mondays might actually be decent days as people will do last minute pugs before the reset.

How to calculate the flask price http://spreadsheets.google.com/ccc?key=0AqsLF_WA3vdDdHNJTU5uVnM2S0E3RHRQQV9GR3FwTlE&hl=en&authkey=CNyN4asF

http://20kleveling.com/JMTCforum/viewtopic.php?f=14&t=6339

Good: you can easily increase your income by undercutting and going into all flask markets,You can also increase you profit by finding a farmer to get the mats cheaper.
Bad: no steady income have to work to get the cash.

- Master of Elixirs is an Alchemy profession specialisation (remember you are stuck with the one you choose) you can learn by completing the quest "Master of Elixirs" given by Lorokeem at Shattrath's Lower City (45.7 , 21.1)
http://www.wowhead.com/?quest=10902

- Master of Elixirs will create 0 - 4 extra elixirs

- It is active for ALL Elixirs and will proc for flasks as well (lucky me had a 5x crit on Flask of Supreme Power)

- The Proc rate seems variable (my total average was 18,71%) As it seems there is a lower proc rate for the low level Elixirs (lvl 5-200 had a 12.85%) with a higher proc rate for the high end elixirs and flasks (27.40%)

- Master of Elixirs only activates "discovery" but does not increase the probability with Elixirs.

potion
Potions are kind of dead in wotlk right now i see now real way to make any gold on potions unless selling low level potions, this might change in cataclysm i don't know but as it is right now potion mastery is worthless.

These are taken from http://20kleveling.com/JMTCforum/index.php a good gold making forums.