My light are old office fluorescent lights that I never even dust. I don't use mylar film. What is it used for? I'm guessing to cover the flats. I use dome covers that I buy with the trays. I wash my pots and trays with a bleach solution and use seed starting mix. I also use aspirin water to water the seedlings but I'll have to check my notes about when and how much. There are articles that claim that it improves seed germination and disease resistance.

I routinely heat sterilize my mix, and sterilize the planter pots with bleach. True that the dormant fungus is in the air, but it appears to not be much in the air inside my converted garage, where my seedlings are growing. That room doesn't vent to the outside and has no HVAC system. No forced circulation. Ever since I started doing this sterilization, I've never had problems with damping off there.

As to lights, mylar film, and for that matter, everything in the room, I have to believe that if there aren't any breezes around in the room, it's unlikely that whatever damping off fungus is resident there will make it to the soil. If you're a spore sitting on a lamp bulb, and there aren't any breezes, you'll probably just stay there. I don't cover my seedlings with anything and don't have any trouble.

I use new seed starting mix that drains well. Also, new trays and cell packs or used ones that I've cleaned and soaked in a 1 to 10 bleach/water mix. And keep the soil moist, definitely not wet. Too wet causes all sorts of trouble. I'd rather have a droopy seedling once in awhile than have my planting mix too wet.

If you are tenting the area with a mylar sheet, it might be good to run a very low speed fan some of the time for air flow. In more open areas I've not seen a need for that as far as damping off goes. It does give stockier seedlings, though.

I've never tried to disinfect anything else for seed starting and don't see any reason to do so. I'd hate to think about trying to have truly sterile conditions around my home. And I doubt it would even be healthy.

I use chamomile tea to help ward off damp off!

With regard to "moist but not wet", I used to have plenty of damping off troubles when the surface of the soil was just "moist", but without puddles. Now, letting the soil surface dry out will certainly mitigate damping off, but in my experience, it also mitigates the growth of seedlings. Very difficult to keep soil moist a half-inch down, and dry on the surface. Packaged mix is often already sterilized. I make my own seed starting mix so sterilization is necessary. Fans are good for making seedling stems stronger, but I never use them when the seedling is very small and prone to damping off. Just asking for trouble.

I should add that the reason that air circulation by fans is recommended is specifically to keep the soil surface dry. If the soil is sterile, soil surface dryness is not that relevant, and blowing air at it that might have fungal spores in it doesn't seem smart. Yes, if you don't use sterilized soil, blowing is a good idea.

I use a good seed starting/potting mix and don't worry about sterilizing things.

Like digdirt said, give good air circulation and avoid over watering. I get excellent results.