Spotify, itunes and youtube have started to normalise all sound so achieving the loudest will soon be a thing of the past and will actually take a lot of dynamics out, still, achieve a good standard of peak volume. But smooth has answered this, sample selection, the mix, processing sounds individually and by bus, if you do all this all it takes is a limiter on the final output or compressor and youve pretty much got a solid mixed and loud track. I put eq meters and other meters on the output both before the limiter/processing and after. If your really stuck for any ideas on what to do, id start by processing your drums bus with some nice eq plugins like vintage stuff, (T-racks do great plugins), this is my personal taste but i does give some nice colours and fatness to the sound, You can compress or limit aswell. Make sure that you dont have unwanted frequencies on samples and sounds, Im working on something that doesnt have any cuts or ducks in the mid freq or barely any, if you choose the right sounds to start with, your not going to have to do as much crap to the sound to make it fit or sound right. But it all depends on the style of music your going for. Hope this is not to much of a scatty respone haha