
I stumbled upon sidewalk chalk drawing back in 1998. My sister, who keeps up with all the hip happenings around town, told me about the annual sidewalk drawing contest that was being held downtown at the artist and farmer's market. It sounded like loads of fun so I decided to give it a try. After that day I was hooked.
First sidewalk chalk drawing entry from 1998.

Contest entry from 1999.

And I was inspired by that drawing to create this finished piece using pastels and acrylic paint on paper.
Contest entry from 2000.

Contest entry from 2001.
I tried a new technique for this drawing. Instead of drawing with the stick of chalk like I usually do, I used a cheese grater to ground up the chalk into a powder and then I added water to make a paste. I used an egg carton to separate my colors. Then I used a paint brush to paint on the chalk paste.

This is me putting on the finishing touches. Notice the shoe on the sidewalk; it was meant to be the shoe that the girl kicked off but it was too small to really be an effective prop:

This image eventually evolved into this pastel on paper and later on this digital image.
Contest entry from 2002.
I used the chalk paste technique for this one too. That is why the top of the picture is so dark...it didn't have time to dry before I took the photo.

And that drawing was one step in the evolution of this finished piece that I created digitally.
Contest entry from 2003.
I went back to my old method of drawing with the stick of chalk. The other way was a lot of work and I don't know that it really looked any better. The only advantage that I really found was that I did not get as much chalk dust build up. But that can be avoided if you blend really well.
My daughter Maia thought the fish in this picture looked too mean. But I liked it.

And here is Maia in front of my mean fish and her sweet drawing of two kitties on a sunny day:

Here are some things I have learned about sidewalk chalk drawing:
Plan ahead.
Prepare a sketch of what you want to do. Try to pick a subject that doesn't have a lot of tiny details. A bold, colorful image works best. Good composition and well thought out color choices go a long way.
Go early and pick a good spot.
Try to get a square with as few cracks and old bits of stuck on gum as possible. Find the least roughest spot - your fingers will thank you (see the "Blend in" note below). You may want to bring a small hand broom to sweep your spot and make it extra clean.
Pay attention to where your space is in relation to where other artists will be sitting and which direction people will be coming from. You want to have an unobstructed view for your audience. Also, if the spots are really close together you could be sitting in your neighbor's lap, which might not be such a bad thing depending on your neighbor.
Dress for success.
Wear something you can get really dirty in. No, not that kind of dirty.
I strongly urge you not to get a manicure the day before the event or plan on going to any fancy events directly after the chalk drawing. If you're like me, you'll find chalk smudges in strangely remote places on your body and you'll swear that you hadn't been anywhere near the vicinity.
Accessorize.
Bring an old towel to sit on or plumbers knee pads. It gets really uncomfortable knealing on concrete for 2 or more hours.
Stock up.
If you are allowed, use the vibrantly colored, large rectangular pastel chalks that art supply stores sell instead of the pale sidewalk chalk that they sell in drug stores. Some contests, like the ones in my town, will have the chalk I am talking about for sale at a reduced price. Here they also allow you to use your own soft pastels as long as they are not oil based.
Let the drawing begin.
I start my drawing by lightly sketching the outline in white or light gray so that the colors I put over it don't get muddy. Then I lay down the first layer of background colors. I'm not exactly sure, because I've never measured it, but I would guess that the size of the area I work in is approximately 2.5x3 feet, maybe a little larger. Anyway, this means that I can reach across the entire rectangle fairly easily. If you are working in a larger space, however, you may need to bring a piece of cardboard to sit on so that you don't sit directly on your drawing when you work on hard to reach spots - unless you want your masterpiece on your tushy instead of the sidewalk.
After the first layer of flat color is done I overlay secondary colors on top. For instance, I might add a little purple to my blue skies or orange to a yellow flower.
Blend in.
Once the background colors are in, I blend them with my fingers. Maybe it's just me but rubbing skin against concrete becomes fairly painful after a while. Unfortunately I haven't come up with a less painful alternative that blends as well. If you're thinking of skipping this part, there are two reasons why it is important. The first reason is that it makes the image look better, IMO. The second, more important reason is because it packs the chalk dust down so that it won't blow off your picture and onto your neighbor's. Let them buy their own chalk.
Save the best for last.
Some people like to do the focal point first so that anyone who is strolling by can immediately see what the image is and be impressed. I like to wait and do the focal point last to create an element of suspense. This, theoretically, will encourage people to come back later, or better yet hang around and watch, to see the breathtaking progression. So when I finally draw the last eyelash the resulting crowd will be there waiting to applaud my final stroke.
Okay, I'm still working on that theory... it could happen.
Seriously, it is a good idea to save the fine details and black outlining, if you do any, for the end because black chalk will smudge itself into all the wrong places (see the "Dress for success" note above) if it has half a chance.
Practice.
Drawing on concrete is a lot different than drawing on paper. If you have an opportunity to practice on your sidewalk at home before the contest that would be an ideal way to get started. If you don't own the sidewalk or pay rent for the sidewalk then please ask permission before you draw. People can be pretty touchy about this for some reason.