Anyone who's ever tried to create foley - the art of adding footseps and other incidental sounds to picture, will know how hard it can be, unless you actually have a foley studio - various surfaces and props to create in real-time. This is generally done by specialized, highly skilled artists who know their craft exactly.
However, these services out of reach for many low budget productions and so often this can be something the composer will have to tackle. The hard part of doing it yourself when using samples is to create a random sequence to the footsteps so they don't appear sampled. Fortunately, FoleyCollection.com (from Peter Foley- what are the chances?) have resleased a collection of Foley sounds - footsteps of various shoe types on various surfaces and cloth and other presequenced bodily movement sounds to make this easier to acheive.
Available as individual footstep types and clothing materials (Concrete Woman Heels, Asphalt Man Shoe, Suit Clothing, Parka Clothing etc) or as a complete collection (€149) you can get busy laying your own foley tracks.