The way I drip acclimatise is;
I have the fish bagged, open the bag, and sit the bag in a bucket; clipping the top of the bag to the handle of the bucket with a clothes peg. That makes sure the bag stays upright and open.
Then I use a piece of airline to start a syphon from the tank into the bag; I tie a knot in the airline so I have the rate I want; I start off with a drip or two every five seconds or so. Wrap the whole lot in towels/blankets to keep everything warm and dark.
Every ten/fifteen minutes, carefully check the fish; as time goes on, if they look ok, you can loosen the knot and let the tank water go in a bit faster.
When the fish's bag is full, lower the whole bag into the tank, let it sink, and carefully tip it to let the fish swim out. Let the fish swim out in it's own good time; don't force it out. Don't worry about getting the old 'bad' water into your tank; you can't dry the fish off before you put it into your tank, so any bacteria/diseases will be transferred anyway, and if your tank is properly cycled and monitored, any ammonia or nitrite will soon be dealt with.
I do this with all fish that have come from another hobbyist's tanks, where I don't know the parameters, and all fish that I get mail order.
It's a hassle, but well worth it, if you want to make sure you don't lose fish from shock; I killed the first lot of fish I bought online by poor acclimatising; I held the bags up to the light to check them, and they all died of shock before i even got them out of the bags; lesson learnt!