In this month's recordings I've really noticed a lack of confidence with basic level mixing. Key instruments such as drums are too loud or too quiet, solos are buried in the backing, energy is lost by leaving rhythm guitar tracks at a modest level. Looking at the demo gear listings, at least 75 percent of them include some form of level automation MIDI, via digital audio software, or from digital desk/recorder combinations. Even simple analogue console mute snapshots can be used to achieve a basic level of automation: split signals to two channels, pre-set them to different levels, and switch between the two during the mix.
When in doubt, automation is a great tool for experimentation with levels, because you can recall your mix and tweak levels up or down a bit. I'd suggest running a few different mixes to your stereo master, keeping notes as you go, and only returning to listen to them the next day. A little distance from the mix enables you to spot glaringly obvious mistakes in level at once, and also to realise when things are right. The mix can then be rectified. You could even decide you want to combine certain elements from several mixes.
Some of you need to go even further back in the recording process. Try recording less instrumentation for the songs in the first place, keep it simple, and get the levels of three or four instruments right before adding more complexity. And remember, in music production, as in many other creative pursuits, less can be more.