Hi timmyde, really you want to be dealing with these aspects during the production process so that you are free to mix as mixing is a different stage really. Production is where you get sounds to fit with each other kind of like pieces of a jigsaw. If parts are clashing sonically they will never sound big! Every sound needs it's own space. Yes you can carve to a certain extent with EQ but remember you are taking something away each time you do that. If you are mixing someone else'e production and it is cluttered then you have two options, 1. Give them guidence on the arrangement and production techniques and get them to re-send a new version or, 2. tackle the mix and make the best of it that you can which happens sometimes too! If you are tracking yourself a word of wisdom, don't go over -12db peak on your tracks. Your will have sufficient headroom and better gain staging then. I hope this helps.