here's what I do when I need a simple "in the box" pseudo mastering:
-export each tune without any dynamis effect or eq in the master bus. you're using those effects later since you have to master an EP, not a single tune, and you have to compare each tune with the overall sound.
-open a new arrangement, import all the tracks, load one channel per track.
-put effects as inserts on each track. the effects you can use vary depending on what's needed, what you hear and your skills. I usually just put an eq to make the tracks have similar frequency response, a dynamic processor (that almost always means compressor, at this stage) to modify the dynamic touch of each track, some other things that could be useful to make the tracks sound similar.
-master bus: I put a subtle maximizer and like said before a dithering effect to convert from 24/32 bit to 16.
-export the whole mastering arrangement and later divide each track with a wave editor or export each track directly from that arrangement.
-listen again. if something is wrong with the mastering, open the project again. if something is wrong with the mix, open the mix of the single track!
this is my personal pseudo mastering procedure, useful if you just want the tracks of a project to sound similar. what real mastering engineers do is more accurate, depending on the medium you will use, the sound you want etc
