I second the RSST as being a fantastic starter Genesis-style
tank atty. The insulated wick hole really makes life easy when starting out, as it reduces shorts.
With regards to multimeters, any old multimeter will do. Make sure you check the internal resistance first (put it on the lowest ohm setting and touch the two leads together, note the ohm value displayed) and subtract that from your reading. For instance, my Harbor Freight cheapo has an internal resistance of .6 ohms, so if my atty registered 2.6 ohms then I subtract the .6 and note that my real resistance is 2.0 ohms.
If you looking for something purpose-built for vapers, Madvapes sells a ohm meter that has 510 (and 808) connection right on it... screw down your atty and flip the switch, instant ohm reading. I have one and it works wonderfully. Unfortunately, they are frequently out of stock on it, and it's a $20 one-trick pony. Worth it to me, as everything I use now is a rebuildable. Here's a link:
Cartomizer and Atomizer Ohm Meter