TalonKarrde wrote:I just joined a L50 squad so I’ll have support for my defense. I also dumped a bunch of medals. Does upgrading shields increase the base scores in a significant way? Thanks for all the good advice

TalonKarrde - Welcome to
Death_Striker Squad

To answer your question you can view all the info about
Base Score on the SWC Wiki.
You can see that Shields add a significant amount to your Base Score as you Level them up so I would keep them to your HQ Level minus 1 or 2 (that is have Level 4 or Level 5 Shields max for a HQ 6).
THE KEY THING is to keep Base Score Low while you grind for Frags. Once you are ready to Upgrade to HQ 9 you can then think about Building and/or Upgrade Defenses like Shields, Turrets, and perhaps even Traps.