Hi Pankace:
An ounce of prevention is worth 100 grams or more
If you have an outside air intake or exhaust put a hepa filter or at least pantyhose on the intake and a bug screen on the outlet and keep them clean. Don't let pets (cats, dogs, rodents etc.) enter the area. If you have a garden outside take a shower and change clothes before entering your indoor garden after being in the outdoor garden. Do the same if you visit someone else's grow, or if they visit your grow make sure they are not transporting a problem into your environment. Clones are notorious for transporting spider mites. I have not grown any clones only beans but I have dealt with spider mites many times over the years. Very difficult to control organically once the get a foothold. I would totally dip and rinse a clone 3 or more times over a 5 day period in insecticidal soap root ball and all before it would ever get near my garden. maybe I am just paranoid about being all wrapped up in a cocoon web with a zillion of those microscopic spider crabs crawling over my eyes nose and mouth sucking the life force out of me

wow was that a flash or what?
Don't plant Marigolds anywhere in your yard or house they are a Spider Mite magnet. I was just wondering if spider mites would migrate from your cannabis plant to a Marigold? Just situate a Marigold touching your Cola wait a day or two and carry them out and dispatch of them. I hope I never have the opportunity to test that idea.
Prevent Bud rot and Powdery Mildew, monitor your temperatures and humidity. Learn about VPD vapor pressure deficit; It will help you feel what the plant is feeling based on the water content of the air around it. The plant is very forgiving about heat and humidity throughout most of it's life but when the buds are fattening up do the best you can to keep heat and humidity down - VPD will go up so keep your eye on the reservoir level provide plenty of air exchange and movement. Translation = keep a fan in your tent/grow room moving the air gently over the canopy circulating throughout the entire grow space and keep your exhaust system running.
Ok what if the worst happens mites - Oooh there is that flash again - Lots of off the shelf options before flowering from chemical garden sprays to Organic sprays just look at the labels. IMHO I don't think any of them are actually safe for human consumption organic or not ( the Death Cap and Hemlock are both organic and can kill you!) - insecticidal soap is effective but you need to be vigilant with your application. After flowering has begun anything you do other than eliminating all oxygen for 2 hours 3 times over a 5 day period is going to affect your final product in some negative manner.
Spider Mites, Bud Rot and powdery mildew are not the only potential problems but they are the ones I fear the most. Nebulas great page is a good source of information.