Funnily enough there's little 'science' to this. Don't go mad with grease is obvious. Clean it off occasionally and redo, but don't get hung up on it. I only remove the wheels sparingly, once in the first twelve months. I clean them on the car and grease the kingpins on lock as is noted above. By jacking up a few inches it's even possible to wipe the drums over (from behind) with Roadster wires. The major risk with large offset wires is 'clipping' the rim with the hammer. My nearside rear has a tiny perfect arc of metal knocked out - clearly where somebody got careless, but it took a few days of pondering to work that out. I have two conventional Thors - big & small, plus the the standard issue hammer. I also bought a second 'hex' spanner (from an MG specialist as it's cheaper) so that I could leave one in the car and have one in the garage. I bought a Ledgerwood stainless tool and a really long breaker bar, and amazingly it will undo fully tightened nuts, but it's very expensive. I have re-tightened with that first, then a couple of hammer blows to finish off. I try to remember to put a bit of masking tape on the nut to take out the slop, but the special tool has no slop.
The MWS gadget looks to be excellent value.
How tight? - really tight is the answer.
Do it in the air or on the ground? - opinions vary. The special tool doesn't 'shock' so rears can be done either way. Fronts need to be on the ground for the initial loosen unless there's a volunteer who can press the brake pedal.
That's about it I think.
