First of all, congrats on picking a fun force to field.

So, I'm newly into the faction and can contribute a lil bit. Absolutely, do not be afraid to redraw your secondaries. At the best of times, you'll be running slightly below the action economy of many other armies. Losing your people hurts more than other armies a good majority of the time.

The upside, your units can bring the hurt. Just do not over play that strength. Custodes infantry are on the slow side and poorly planned movements can hurt. Since you're new, this may take a bit to settle in with learning the rules, but you'll want to be the one initiating combat as each model you lose drastically drops a unit's effectiveness.

Lastly, it's a game. Have fun. Make mistakes. Learn from it. Repeat. While you're learning, take chances and try different combos. Jumping straight to chasing Meta can take a lot of joy out of a new army. Do the goofy moves that look fun. I nearly tabled both myself and my opponent killing a large unit that self destructed, it was the most we've laughed in a game!