General set up tips:
Find full suspension travel front and rear spec. in the manual or www.
Measure "sag" from suspension fully topped out (in case of a R1xxxGS on the centre stand) to the position where it sits with bike fuelled, on its wheels and you seated normally. Loaded with whatever you plan to take along: Wife or GF, luggage, kitchen sink

The measured "sag" should ideally be around 1/3 of the full suspension travel. It may be a bit more but should under no circumstances exceed 50% in the front. In the rear it is often not avoidable to run around 50% (with the kitchen sink strapped onto the back).
Aim for more sag if you do slower more technical riding. OK, not for the R1xxxGS

Damping: If the bike rattles badly over corrugations, the suspension feels harsh and ill responding and if the bike lacks traction on acceleration on bad tar and lacks steering precision in fast corners on poor tar your damping is likely too high.
If the bike wallows on fast tar over whoops and undulations in the road surface whilst cornering the damping is too low.
If you have separate dials for compression & rebound damping and maybe even low and high speed compression and you don't know what to do with it go and buy a friggin' suspension setup book

Always set spring preload first before you do the damper.
Never change two settings at a time (without testing results in between).
Note your starting set up to be able to return to a known ok-ish setup if you fcuk it up

Second last but not least:
Do not pussy foot when changing damper settings:
Ride the bike with damper fully closed - half open - all the way open.
Eliminate the setting which is most awful.
Continue with the remaining two settings and a third one half way in between.
This will get you to a very good setting with no more than four test cycles rather than changing tiny bits for a whole day and not noticing any difference.
Finally: Damper settings are compromise. Nothing works everywhere and under all circumstances. Learn to find a good compromise or learn to set the bike up for gravel / tar / good & bad roads.