my method is as follows:

connect chain to smallest chainring and smallest cassette cog and cut it so that it is just short enough to be tensioned by the derailleur spring. provided the derailleur has the capacity to cope with the largest chainring and largest cassette cog, everything works a treat. is there a better way? cheers

Traditionally put the chain on big ring and biggest cog and add a link…

Thought it was two links?

i put both mechs in big big and pull the chain together. when i have the mech pulled as far forward as possible in this (so so wrong ratio) i cut off the pare and join it. that way you know you havnt cut it short. i done it so many times its usually 9 joins i remove!

Big to big (no mechs) plus two links.

turnipforgeindustries that's one of the two ways shown on Parktools website, and my personal favourite method.

Big/big, add a pair and cycle the suspension to make sure it doesn't get too tight anywhere in the stroke.

then run through the mechs.