Hi Russ:
Welcome to the forum. You're going to like it here. Tons of good advice.
The main things are probably:
--- A good launcher system based on a relay, heavy wiring, and a powerful battery.
--- Wiring the igniters in parallel.
--- Balancing the igniters (similar amount of pyrogen on the tips, similar electrical resistance, etc.)
--- Making sure the igniters are properly installed in the motors.
--- Keeping your thumb on the launch button until the rocket is in the sky. Flying single motor rockets tends to train us to release the button once we hear the whoosh. As clustered motors will probably light at slightly separated moments, despite our careful preparation, it would be possible to cause only part of a cluster to fire by releasing the current too soon.
Jim Flis, a master rocket designer and a cluster expert of long experience, gave a good checklist toward the bottom of the first page of
this thread. Jim's company, FlisKits, has some really nice cluster models too.
Finally, keep in mind that with 5 Ds, your safe distance (i.e. the minimum length for the launch controller wire) has gone up from 15 feet to 30 feet. Don't skimp on that.
Might want to practice with a two-motor cluster before flying five, just to get in the swing before risking a larger rocket. That's advice Jim gave me, and I believe it's good.
Steve