It's kind of a necro bump, but I was looking here for tips to get from 100 to 110 (I found some helpful info). Anyways, I saw this and I thought I'd help.
First up, if it's your first craft skill, take a gander at this:
https://www.bg-wiki.com/bg/Category:Craft
And for Alchemy specific things:
https://www.bg-wiki.com/bg/Alchemy
What I did is just look at the big-ol list of recipes find something 5-8 skill levels above my current skill that is cheap and easy to get the materials for. Gather/buy/craft the materials in bulk. Donned my Alchemy+ and skillup+ gear, pop a kitron macaron, get Ionis, get the alchemy synthesis support and go sit in adoulin and craft for 8 minutes. Rinse, repeat.
Helpful gear:
Trainee Sword while you're lower than 40 skill,
Alchemist's Torque for always,
Midras's helm +1 for skillups (Long quest, but worth it),
Shaper's Shawl, if you have it or want to spend the money on it. (I did not.)
The order I went on Guild Points was:
Alchemy Emblem (Veteran) to synergy into
Alchemist's Stall for a whopping +5 alchemy skill always ->
Caduceus ->
Way of the Alchemist (to get to 100+) ->
Alchemist's Apron.
Get whatever Key Items you happen to need along the way. I avoided them completely though.