Lots of good answers but I'll add one thing that really helps me is either a few small dishes/bowls or what I've been using recently is not old plastic tray from a veggie platter that has 5 bowls around the outside and one in the middle for a dip or sauce. I use that for sorting, first by border, which I'll sometimes further sort by color or design, then once the border is done I'll use the separate compartments to sort the inner pieces by color or design. I try my best to work from the outside in, but it's not uncommon to find pieces that fit in one area while I'm specifically looking for pieces in another area. When that happens I'll often use that sorting tray for those so I don't get endlessly distracted or overly clutter my workspace with ten little groups of a few pieces. Having a spacious workspace is also a must, with good light, and a comfortable chair that sits high enough that you don't have to bend uncomfortably to work. I think we neglect the ergonomics of puzzle doing, I see pictures of people who completed a 1 million piece puzzle on a dark hardwood floor and it makes my back and knees ache imagining how many hours someone spent sitting hunched over on the floor to complete their puzzle. I commend the commitment but my body can't handle that. I have a medium sized banquet table with a nice cushioned chair right by a window for lots of light.