Before you start DIY Eliquid Mixing, you'll need a few supplies and equipment.
Mix By Volume Or Weight
There are two basic ways to mix e-liquid, one is by volume, the other by weight. Mixing by weight is by far the simplest with virtually no cleanup. If you mix by volume, you need to purchase syringes or pipets which you either have to clean to reuse or use a new one with each flavoring which can be costly and time consuming. You can purchase syringes and pipets from Bull City Flavors though I suggest mixing by weight.
To mix by weight, all you need is a gram scale that has a read out to the 0.00 grams. AWS sells a great scale for around $25-$35 depending on where you purchase it. I bought mine from Amazon for around $28. Believe me, it's a great investment.
You will also need bottles. I get my bottles from Dropperbottles.com. You have to buy 100 at a time, but it works out to around $0.30 each if you buy the 60ml plastic bottles. Glass bottles are more expensive but may be better if your e-liquid is going to be sitting for months before you vape it. If you don't want to buy in bulk, Bull City Flavors has a pack of 60ml PET Chubby Gorilla Bottles (5-pack) for around $2.10.
One last thing you will need is an e-liquid calculator. Now this is not a physical object but rather a web-based or downloadable app or as a phone/tablet app. I use Alltheflavors.com to calculate my recipes. It's 100% free and has a fantastic user interface. Alltheflavors.com is also a great resource for mixers to keep track of their flavor inventory, post recipes and also see what other great mixers are creating from all over the world.
There are many other apps like e-liquid-recipes.com and VCCalc.VapingCommunity.co.uk that can be used on your phone/tablet or PC/MAC. Which ever you use, e-liquid calculators are essential for getting your percentages correct in your recipes.
These supplies and resources are all you need to get started mixing. And with a little practice, you'll be able to create recipes that rival some of the best e-liquids on the market, and at a much cheaper price.