Derailleur installation adjustment method I recently installed a SRAM XX1 crankset on a mountian bike (first build) in the instructions they want you to:
1. Adjust for the high
2. Adjust for the low
3. Install the shifter cable 
4. Adjust the B-screw
5. Put the chain on
6. Adjust high and low again.  

I didn't find this to be particularly useful because I couldn't get the chain to align. I found out by talking to a few people that after I put the chain on, it was hard to align the shifter. I talked to a few people and they said after the chain goes on you should undo the shifter cable and then put it back on. After I did that everything worked perfect.

So I have a few questions: 
Is there a method to installing derailleurs that works? Does it vary between brands? Are there any tricks I should know?
For B tension screw I suggest you to just have look at this video
 B tension adjustment
Steps to adjust your rear derailleur


Drop the chain to the smallest cog of your cassette.
Tighten the cable.
Loose the cable tention by turning the cable tention screw.
Align the upper pulley just benith the cog and slightly inward using the H high limit screw.