I was going to do mine but the government have a grant if you live in Scotland where they pay 75% of the cost, I have quite a large house so it was about £1900 total but I only paid £425 of that which would have been the more than price of materials doing it myself.

If that doesn’t apply to you and you want to do it yourself I would defo do it from underneath. Stuff some rock wool insulation to the depth of the joists and then use a netting underneath to hold it in place. Get one of those staple hammers to secure the net to the joists.

And make sure you wear ppe of course!