Go with a dual body Taprite regulator from the start.
Get the fridge with the freezer on the bottom this time (current one is freezer on the top).
Already have a 20#, 10#, 5#, 2 2.5# and a mix of paintball CO2 tanks/bottles.
Get the Leland regulator MUCH sooner than I did (for use with the paintball CO2 bottles).
Got both the Beer Gun and Bowie bottler setups. Next time, just getting the Beer Gun. IMO, MUCH easier to use.
Install shutoff valves on one side of the bulkheads that go through the sides of the fridge.
I already plan on getting either another (larger) brew fridge or making a keezer when I move in a few months. At that point, I might start using 5 gallon kegs, but for now I'm really happy with the 3 gallon kegs I use for almost all my batches. Since I put about 6.5 gallons into fermenter, I get about 6 gallons out. I might change that when I start fermenting 10-12 gallon batches (got the keggle made, so I'm good to go there)...