I tend to make very distinct seperations in my workflow . The simple version is:
1) Tracking/composing. All recording of instruments ( acoustic and virtual) and voices
2) pre-mix prep. This would include fixing things like noise issues if re-recording is not practical. I now include the initial parts of my gain staging here.
3) Mixing. If all went as planned in steps 1 and 2, it should practically mix itself. Doesn't always work that way but when it does the decisions I make at this point come down to rotely carrying out the obvious combined with creative preferences. My goal here is to get to a point where an amatuer would feel it sounded mastered.
4) Mastering. If it is feasible I have someone do the mastering seperately in a different location. I know some just make a mastering bus and if that works for them I won't knock it. For me, I feel that my ears already feel it's "correct" and any "mastering" I do is likely just reinforcing any mistakes I may have made. When I do my own mastering I still try to do it with fresh ears at different location. I mostly master in sound forge and occasionally T-racks. I find the hip-hop/pop/rnb crowd like the results when i use t-racks