I BIAB, 23 litre batches in a 30 litre boiler. If the bag is a little too heavy, I get my wife to help out. She either helps to lift the bag, or I lift the bag whilst she puts the cooling rack on top of the boiler once I've lifted it high enough. I never squeeze the bag as you end up with super cloudy wort when you do, which would defeat the object of using my recirculation system to "vorlauf" before draining the boiler to sparge, and I always "sparge". I also build a recirculation system into my boiler though, so it's not quite as simple any more, but on the plus side last brew day I got 90.6% Efficiency into fermenter according to my software...
Without recirculation, the 2 best bits of advice I could have done with on my first BIAB brew were:-
1) Get your mash pH right, you get better efficiency that way.
2) Stir well when doughing in, making sure to lift the grain off the bottom of the bag into the liquid fully. Do the same every 20 minutes through the mash.
These 2 things massively improved my efficiency starting out. Better efficiency means you can get the same OG with less grain, which is really helpful when you BIAB. Oh, and don't stress that your wort WILL be cloudy going into the boil, especially if you do squeeze the bag.
Before recirculation, I used to be able to get 80% and up efficiency with BIAB, but would end up with very cloudy wort.