In my opinion, you shouldn't split sounds too much as it can often mess with the dynamics, so I can't recommend using too many multiband plugins. Instead, try to think about what needs to be wide and what doesnt, keep it simple. In most cases it's enough to just make the whole sound either mono or stereo. And remember, it's not the overall width that makes something sound wide, it's the contrast between mid and side. My rule of thumb is to keep everything that has to sound precise (low basses region and drums, lead vocals) more mono, I leave the stereo space for sounds that require it to work (pads, chords or sometimes background vocals).

This is something I think many people overlook when it comes to multiband stereo processing.  Multiband stereo processing is something that should be used only to make slight balanced changes to a sound or else it could easily ruin the stereo characteristics of the original sound.  Instead, I recommend carefully choosing which sounds you want to be widened entirely.  Most of the time, you'll end up widening sounds that are mostly focused around high frequency content, meaning you won't end up with over widened low frequency content anyway.

Depending on the track, clipping is a really great tool when used carefully.  I personally use it way too often.