Retro Man had pretty much all of the good advice on starting, good job Retro Man.
Just wanted to share another vendor that has WICKED deals on DIY stuff. They have DIY kits, good deal on their nicotine and VG/PG, and the cheapest flavorings I have seen, 4 ounces (120-125ml) for $6-10. Free shipping on over $75. 120ml, 100mg nicotine for $16. I just placed a $45 order from them today for the rest of my DIY liquids.
There is also a few calculators online to make your mixing easier, Google "DIY
juice Calculator" or "E
juice Calculator". They also have some apps on Android, and surf around the forums here, a lot of people have posted their recipes.
Are you looking to make it for personal use or to sell it?
Forgot to add the vendor that sells the supplies.
Heartlandvapes on Google