Theresa's link is A+
Before you go hog wild - I would make sure you have a few recipes in mind before you buy flavorings - many, many of us have flavorings we will never use because when we were first starting out we saw flavors that "looked like they would be good" and maybe weren't or didn't go with anything else later
Once you find recipes you feel confident you will like (I started by finding DIY clone recipes of juice I knew I liked) - do your best to use the exact brand of flavoring the recipe recommends - different brands almost always taste different - even if both taste like an apple, it won't be the same apple, for instance
Most people start off with 100mg nic, PG - it mixes a lot smother than VG-based nic
When I first started, I just recycled old juice bottles and washed them out until they started falling apart so bad I eventually did buy new ones, lol
If you want to start inexpensively, buy a few cheap syringes and mix by volume - but you can get a decent mixing scale for under $15
