I let all but a little air out of my ATV tires and get great grip on the ice. You want them almost flat.

I don't have chains, but I have not needed to plow more than 4" off of the ice yet. The black ice we had a little while ago was tough to get started on though, but it worked.

For plowing, you really need to plan a good pattern to get more than a few inches off of a larger pond in a reasonable time. You don't want to have to back up a lot if you can help it. 2-3 large overlapping ovals while pushing snow to the outside edge with an angled plow seems to work best.

Expect to freeze to death in the meantime. All I know is those thumb-based accelerators leave you with a very numb appendage. Wear snowmobiling mittens.

Lastly be careful of piling up too much snow near areas where the ice may be thin. I had an "incident" where the weight of the snow plus the ATV and myself broke the ice at a steep angle. Luckily I was able to goose it in the slush along with the plow still on solid ice to get out. I had visions of my ATV and myself frozen into the pond until late spring.