It's best to do each sim separately, at least at first.There will likely be things you want to adjust, and it's quicker and easier to do that if you're running one sim at a time.

Go from inner to outer. If your top overlaps the pants, do the pants first, then the top.

I would do the hair first, just because hair is more likely to have memory issues. The less stuff in the scene, the better. Also, I increase the hair density for the final render (without running the sim again). The results aren't any better if you run the sim at high density, it just takes a lot longer.

If you're not familiar with the cloth room, using the default settings is a good start. I usually reduce the collision depth and collision offset a bit, maybe to .4 or .5.

For this walk cycle, I ran the hair sim first, then ran the cloth sim.