In my established areas, I just let all the leaves stay...don't even try to cut them up. All the native plants can push through. I have used pine bark mulch, the small size but not the soil conditioner one, in new areas when I planted in spring and I had no leaves. Pine needles look too artificial in my natural setting, but some of my friends use it. In areas in which I do not have my "special" plants such as trilliums, I have used a product called Snapshot as a pre-emergent. It is expensive but fantastic! I put it down in late Dec. or Jan., and I have no chickweed or other winter weeds...and it keeps that Japanese stilt grass from emerging in the summer. I use this only in the shady areas as my sunny areas are all fields that we just cut and don't worry about weeds there.

First, cut down and kill off the weeds as best you can. Next, newspaper covered by wood chips is a good weed-suppressing mulch. Follow that up with planting in your favorite natives. No system is perfect but you can make things better than they are.

What is a weed? Are we talking exotics or just weedy natives, like Geranium robertianum?

I use leaf mulch. I shred the leaves with the lawn mower, so the mulch looks nicer and doesn't blow around.

I think in the context of this particular discussion a weed is simply any plant you don't want. Ecologically a weed is one thing and agriculturally or aesthetically it may be other things. I happen to like a lot of plants that others consider to be weeds -- like jewel weed for instance.