Is it OK to clip single tracks channels and only make sure I don't clip the master fader at mixdown?

[maanga]

It all depends on how many tracks you are running, what the mix is finally used for and the type of music itself.
For track levels, I use -18 dB when the number of tracks exceed 20, and -6 dB when the track counts are lesser.
If you automate the tracks and the level increases in between, you still have some buffer.
If some of the tracks go to a bus, the bus signal will add up and may cause problem.
Your cup of tea may be different. Whatever you do, keep it as a regular habit and improve from there.
Regards.