predatory bugs are great but can make processing challenging due to frass, bug shells, etc.
IMO, entomopathogenic fungi and bacterial fermentation solids (like B.bassiana and BT products) are the easiest way to deal with/prevent pests from crossing an economic or damage threshold for pests.
That being said predatory wasps are probably my favorite beneficial type to add to a greenhouse setting as they are highly mobile, predate high numbers of pest insects, often propagate themselves at rates that correlate with pest instances, and can persist for the entire grow cycle (or longer). Beneficial nematodes are a close runner up to deal with high pops of gnats, thrips, stupid root aphids, or mites.
pre-emptive applications of rotating entomopathogenic products/organisms works best, in my experience, for a variety of crop types fruit or flower.