Use good soil
Maintain an absolute sterile growing area
Do not wear "street" clothes into the growing area -especially shoes
Do not pet your dog/cat and then go into the grow area.
Do not let animals in the grow area.
Grow during the winter when outdoor pests are dormant
If possible, keep plants separated (as opposed to jamming as many as you can fit)
Observe your plants close up several times per day, if possible. Look for anything suspicious and take appropriate actions immediately
As far as using bugs to kill other bugs...If you get a mite infestation, for example, then not even an army of beneficial insects is going to get rid of them. By then, it's too late, anyway, because you should have been on top of the first signs of them before they became infested. Oh, and ALL bugs poop -beneficial or not. That's all I'm going to say.
I rarely use chemicals because of my strict adherence to cleanliness, but when I have, it's been something with Spinosad in it (Captain Jack's Dead Bug). I have used diatomaceous Earth when the plants are in a vegetative stage, but never when they are flowering.I've never applied any chemicals to a flowering plant -ever.
Outdoors, you do what you can to work with Mother Nature, but indoors, you should have complete control.
"An ounce of prevention is worth a pound of cure" -someone