My preferred method is to completely rub out a small amount and drop it into the bowl. Then I take one flake and tear off thumb sized pieces (depending on the width of the bowl) and layer those on top of one another until it reaches near the top of the bowl. I then top it off with another small pinch of fully rubbed out flake to make it easier to light. Some people use scissors or a knife, but I can't be bothered and simply pinch it with my thumb and pull it off.
I find lighting a flake without a little fluff on top is pretty difficult to do, so the little pinch of rubbed out tobacco serves to get the pile going easily. The rubbed out pinch at the bottom serves to make sure the draw remains consistent because I find that sometimes a piece of flake can bung up the air hole if it gets folded over it during packing and it can make the whole pipe impossible.
Some flakes need a bit of drying first, I think you'll find. For me, they tend to be a little more moist than most tobacco. It's a good cut for virginia tobacco, in my opinion, but I think the majority of flakes are virginia forward.
I like the variety and flavour. It's good to really try and get the flake going without fully rubbing it out so you can notice the difference and how it changes the smoke. I find the taste to be completely different if it's kept in flake form v.s. fully rubbed out. Probably something to do with heat, but who knows? It's just different to me and I think it's worth experimenting with before going the route of always rubbing them out.
Not that there's anything wrong with rubbing one out once in awhile... A guy has to do what a guy has to do.