A good way i found to start off was to delace a bicycle wheel and relace it up. A bicycle wheel is harder to do than a motorcycle wheel, so practicing on one & getting it right makes it a good idea because it gets easier for the m/c wheel. An opportunity to get a good feel for what needs to be done. Motorcycle rims don't flex anywhere near as much as a bicycle rim.
Install the inner spokes first, then the outer spokes. Ensure spoke lube or oil is on the nipples.
0.5mm for radial runout and 0.5mm for lateral runout is good enough, as mentioned above.
The rim will have a kink where it is joined/welded. Don't try and get that perfect as you won't be able to. On that, just aim for a good average.
Basically there are 4 items that need iterating through. They are:
(1) Radial runout
(2) Lateral runout
(3) Dish
(4) Tension
Go through steps 1 to 4, then repeat. Keep going until all 1 & 2 are within 0.5mm & the wheel is centered & the spokes have equal and firm tension. You will find that through each iteration, things will take more and more shape. Don't try and get everything perfect first go around. Start rough and it'll come together every iteration.
Fit a new tyre, balance and it will be like a bought one.
I've done both mine to within 0.5mm they are extremely smooth at highway speeds, no different in smoothness to my 2002 blackbird.