Most believe that the Scatter Laser, Shuri-Cannon load out is the best for Serpents, but You may wish to use Bright Lances... so it is best to invest in some mini magnets and magnetize your loadouts. I wish I had with my EML WS that I was using for 4th and 5th ed.
Keep the DAs plain.
Magnetize the weapons platform for the Guardians. You never know if you will want them cheap, AP2, lots o shots, or tank hunter shots, so best to keep all those options open.