My Tacky-Ass(ault) support build.
This is one of 6 builds I run and one of my favorites. It's straightforward. You follow around, behind, beside, all over a D3 spamming Defib and laying down armor melting suppressing fire. D3's your mobile shield and you'll constantly be dodging bullets and diving for cover, suppressing and wearing down enemies and basically just softening everything up while they hide and focus on the tank.
Also depending on how much healing your group has I often switch 'Stopping Power' and 'Critical Save' around or 'Shock and Awe' for 'Steady Hands'.
Just as a FWIW type thing it's easy to get the the 30% bonus to SP from Tact's which means your Defib hits for over 220k healing and another 22k/sec for 10-secs and takes under 14-seconds to cooldown. Your tank will love you and may want to seriously consider a Vigorous Chest and/or Resourceful Backpack with you around.
One thing to note about this build is I don't go for kills with it. Typically your tank is designed to kill, so while they do that, play to the strengths of a Tacky-Ass supporter, spam that Defib and don't neglect your turret ;)