How does one clean a messy fstab ?

[SYNass IT Ubuntu / Linux]

Hello Ubuntu experts and users
It sounds that my earlier intentions with my multi-OS setup seem to
ambitious and 
somewhat too risky !?!

Got some recommendations and warnings not to do from reliable sources
and 
so I decided to step lower and more simple !! ;-)

Currently I need your assistance / help how to clean my fstab best and
easiest:
Lucky, the system starts and runs and seems not to have any acute
problems. ;-)

But what is the correct and efficient sequence of tasks to bring the
fstab and 
may be other system files back to a clean proper status ???

Do I start and rely on date from "blkid" and then correct fstab ...
... or what else do I need to observe to get back successfully ?

TIA for your very appreciated helping feedbacks.

Cheers, svobi