1. Read as much as you can from the mods makers mod page.
Hrm could be better here
2. A general idea of how JSGME works (e.g the last mod installed will overwrite the file that conflicts).
checked 
3. And trial and error.
problem is some goodies could be left out and I wouldn t even know
You can see my mods install order here --->
Link
That was a long list 
Just ask if you need help. Many people here will do their best to help.
checked
A megamod will naturally always lag somewhat behind the single mods and I can live with that.well off to check the contents of the latest new ui s
happy hunting