Begin mixing by bringing all of the recorded tracks to their lowest possible volume.
Raise the volume slowly on the drums. Add effects, equalization, compression or limiting to the drums until they sound the way you think you will want them to sound in the final mix. Additional tweaking will be done later as the overall mix takes shape, but you must build the foundation before putting on the roof shingles.
Slowly bring the bass up. Add any additional effects or processing as desired until the bass and drums work well together. If you need to do any editing on the drums or bass, now is the time to do it. The bass and drums should be locked in together so that the instruments create an easy-to-follow rhythm and groove.
Bring the main melodic instrument up in the mix. Commonly, acoustic guitars, pianos or electric guitars will be the main melodic instrument. If you wrote the song on a certain instrument and played that instrument during the recording, it is probably responsible for the main musical melody of the song. Process the track as necessary and bring the volume up slowly until you have found where you want it.
Add the next instrument if applicable in the same fashion. In a typical rock band setup, the next instrument to come in would be the lead guitar, following the rhythm guitar or piano in the last step. Process the instruments as needed and find the appropriate volume.
Continue this process on each instrument remaining.
Consider where your instruments are in the stereo field if you have not already. If you already know where your instruments should be panned, do it now. Typically, drums and bass are near the center, if not dead center. Melodic rhythm instruments tend to be a bit further to the left or right side, and lead guitars or musical parts like horn solos tend to be even further to the left or right side. Though there is a traditional way to do this, there are countless successful records that buck these trends, so do what sounds right to you.
Bring up any vocal tracks until they are at the volume you want. You may have to reduce your instrumental tracks at this point if your overall mix is too loud, but this is easy to do because you can simply decrease every instrument by the same decibel amount. Process the vocals and pan them where you want. Traditionally, vocals are near the center, but again, this is really about personal preference.
Check your overall mix volume. You don't want a distorted mix, so make sure your mix does not go above the zero-decibel mark on your mixer, DAW or tape machine. If your mix is too loud, you can reduce each track's volume or bring down the stereo faders if you are working on an analog console or control surface.