Basically you want a drip shield or two and some bridgless atomizers. 510 and 306 atomizers both will fit on just about everything and 901 atomizers will require a 510 to 901 adapter. If you decide to get 510 or 306 atomizers I'd say get a 510 to 510 adapter anyways as sometimes they are required. Also, 306 atomizers require a special drip tip just for 306 style atomizers.
You can pick the ohm of the bridgeless atomizers. If you're using a variable voltage or wattage
device you can use any ohm range, but more people favor 2 ohms or more on vv or vw devices. If you are using a mechanical mod or unregulated
device you'll probably want the 1.5 ohm atomizers.