There ain't no secrets, just learning curves.
Your problem might be that you need to place the instruments better in the sound spectrum, using panning, reverb, eq, etc. When instruments are properly placed, they tend to conflict less with each other. You should be able to hear each instrument individually when things are mixed properly.
You have left to right to work with (panning), front to back (usually reverb), and up and down (eq). Don't eq anything solo'd. Eq it while it is in context in the mix. Frequently what may sound horrible when solo'd, is exactly what is right when placed in the mix.
There are many ways of working. One approach might be to mute everything except the bass, kick, snare and lead vocal. All of these are normally panned center. I usually use the lead vocal as my guide, and set the volume of everything else in realation to the lead vox - since that is usually the focus of the song. Once you get these 4 working together, start bringing in the other instruments one by one. Here is where you are probably going to start panning things. You may have to go back the readjust the volume levels on some of the original instruments, but try and leave the lead vox as is.
Try and make sure each instrument can be heard and has a place in the mix. Also make sure the mix stays balanced - not too much left or right.
Hope that helps somewhat.