If the one person tent is rectangular, you just stake out corners. Make sure the sides are at right angles.
For my 5 sided solo mid, which is the only one in existance (although a Trailstar is sort of similar) I stake the two corners on the long side, pulling the fabric mostly tight. Then eyeballing the two adjacent corners. Then put in the pole and stake out the fifth corner. Then adjust the 3rd and 4th corners.
Since it's an odd shape rather than a square or rectangle, it's a bit trickier to get set up. Sometimes I have to pull out one of the 3rd or 4th stakes and re-place. But this all takes maybe one minute so not a big deal.
I was just thinking, it would be better to set first 2 corners, then put in pole and stake 5th corner, then do the other 2 corners. I'll try that next time.
One thing about a square or rectangular mid is, the 4 corners have to be on the same plane or the 4 ridges won't all be taut. With the 5 sided mid, you have more adjustability, sort of like a Trailstar.