[raketenjagdpanzer]

Here's a few pointers:

If you're going to play online I cannot recommend Roll20.net enough. Despite the name it is system-agnostic. It doesn't require a d20 gaming system. At it's core it is a whiteboard system you can have tiles on, and associate characters and characteristics with those tiles. You can also have sound effects, music, etc. There's a "fog of War" effect where you can simply have the map blacked out where characters cannot see (this is great for fantasy gaming where players are moving through a dark dungeon, for example). Players and the GM can draw on the map; it can be a blank "sheet of paper" style map, hexgrid, square-grid, and so on.

With that said it's not perfect: it's audio subsystem is terrible. The best workaround for this is to embed it in Google+ (there's an option at start to do this, and any time you open your campaign you can start it in Google+ Hangouts and invite people in). Google's audio chat system worked flawlessly for my group.

IF you're averse to G+ hangouts (and I can understand that) I recommend using Skype or some other VOIP system rather than Roll20.net's included chat system.