Valin - I am by no means an expert and I would consider talking to Bob
Nuckols, but I did a few common sense things and so far haven't had
any issues with electromagnetic noise.
First follow what the avionics install manuals suggest.  All pretty
much designate whether the shield should be grounded or left "free"
and what type of wire to use.  When the shield has to be broken to
jump a switch or connector, make the pig tail short as possible,  <
than 6".  I also ran most of my sensor wires down the left side of the
plane and the big power and grounds down the right.
It seems like the biggest issue are the strobes.  I have the aeroleds
and although some had issues, I used shielded cable and grounds
everywhere and not a peep is heard over the com.

You also might want to give Jon Hadlich a call from AI systems.  He
has a lot of experience in these issues and is an overall great guy.

my 2 cents.  BTW if you need any wiring diagrams, I would be happy to
share what I did

Dan Ballin
N386DM