You can go a couple of ways using a cartotank, which has pretty carefree use once its set up, and can hold a decent amount of juice (3.5ml) that should last you most of a day easy.
Most vendors sell a variety of the above DCT tanks. The larger size hold 6 ml of juice, the slimmer size holds 3.5ml. Both will use a
45mm length carto, and you can put either a single coil or dual coil in them. You'll also need a drip tip for a mouthpiece. My Vapor Store sells these in a kit for $21.50 which will include the tank, a drip tip, and 5 cartos that are prepunched for a tank.
510 Pro DCTank Combo
The slimmer 3.5ml tank looks better on an eGo type battery. An eGo cone cover (pictured below) will hide the connection gap between the battery and tank, and also add more sturdynest for the setup. Pre-punched cartos are available so that you don't need to punch your own. Otherwise you will need to pick up a carto punch tool for unpunched stainless cartos.


Above images show DCT tanks on various sizes of eGo batteries, on a eGo Twist, and the eGo cone cover.