Stone walkways can provide a safe, attractive, and durable path in a wide range of landscape circumstances. Stone walkways work best when they are level in all directions, especially left to right. Stone walkways on a slope should incorporate steps if possible unless it is specifically designated for wheelchairs, walkers, or other ADA criteria. In those circumstances, there is a specific maximum grade of the slope.
Large, single stone slabs with a minimum depth of 2 inches work well in walkways. Thinner stones tend to move and/or crack. I do not suggest using brick in walkways unless they are mortared onto a substantial concrete footer. Brick does not have the mass to resist the heave of soil, thus most brick walkways do not have a level plane on top, making for very difficult walking.
In general, a minimum width of 18″ is best for walkways. This allows most people to have both feet on the same stone at the same time. I build most of my walkways at 3′ wide, which allows two people to walk adjacent if necessary.
Often, stone edging is needed to contain the gravel beneath the flagstone of the walkway, or to keep soil or grass from spilling over onto the walkway from it’s borders.