Limiters on Master - please help

EDM is typically compressed more aggressively than other genres. Only hip-hop is squashed more than EDM. Being neither a practitioner nor fan of either genre, I can only give hypothetical advice from a distance.
 
Contemporary EDM's dynamic range is often less than -8dB, although I understand there is a movement afoot to get back to wider dynamics. Well-respected mastering guru Ian Shepard makes a compelling case for more conservative bus compression for the genre.
 
If I was pressed into service to master an EDM piece, I'd start by inserting the limiter and setting the brickwall limit to -0.3 dB, then bring up the input level until the output hits whatever target RMS value I'd chosen. It's either going to sound good, or not. If it doesn't sound good, then maybe my RMS goal was overly aggressive.
 
What that input level will be is impossible to say, as it depends on the mix. You might need your limiter to give an average compression of only a couple dB if the mix is already loud. As a general rule, you want to give your limiter some room, regardless of genre. If you see the amount of compression being constantly more than, say, 6dB then it's possible your mix is too loud to begin with and you've left the limiter no room to maneuver. For that reason, your unmastered mix's loudness should be conservative, peaking at less than -1dB with an RMS value less than -6dB (-12dB for non-EDM genres).
 
Multi-band compressors (or multi-band limiters) are mostly used to squeeze out the last dB or two. However, a multi-band compressor in front of a broadband limiter can be used with gentle settings and still enhance bass/kick punch. Check out the free Kotelnikov compressor from TDR, not the easiest plugin to learn but once you figure it out it'll be quite effective in this role.
 
Watch the following video closely. You might want to play it more than once, as there are several nuggets of wisdom in there.