For diapers & really dirty loads, let the washer fill up with water, then turn it off and pour in about 3 gallons of water, either through the soap dispenser (runs directly into the drum in my machine) or by opening the door & pouring it in. This will increase the water level, but it still won't go to the door, so no worries about that. This extra water REALLY helps.
Pre-dissolve anything powdered in water before adding. Things like oxiclean, powdered detergent, etc etc. Just pour it in a cup, add water, mix then pour into the machine.
You can soak in a FL! Just load up the machine, let the machine fill up, add in whatever soaking cleaners (soap, oxiclean, bleach, baking soda, etc), and then turn it off! Add in the extra 3 gallons from above, and that's it. Soak for as long as you usually would. It does help to turn on the machine every now & then to give items a tumble so that each item spends an equal amount of time on top & on the bottom.
Leave the door open when not in use. Otherwise there's ton's of funkiness.
Use about a tbs or 2 of detergent. Less if using a regular detergent. More if cleaning diapers. Since figuring this out, I've gone over a year using the same bottle of detergent I bought from costco!
Ami