Audiotent Tip 336. Panning.
Positioning your instruments left or right in the stereo field is a great way to get more separation in your mix.
Make sure you don't pan two instruments of the same frequency range in the exact position, otherwise this will not help to eliminate masking.
Try panning similar instruments opposite to each other to maintain balance in your mix.
For more information on masking, read our Frequency Masking Explained blog post here.