Chalks
Any kind of paper can be used with chalks. Just note, the more tooth the paper has, the better application you will get. The chalks/pastels will adhere better leaving more color. Chalks will adhere to smooth papers, but the color stain will be lighter.
Note that the chalks are not glued down so they can be removed and you can use them directly on the paper to make neat backgrounds and such. Applicators can be q-tips, pointy craft q-tips, makeup applicators, the little fuzzy tipped applicators and paint brushes. Each type of applicator will apply the color differently. Experiment to find out what you like best. Paint brushes will give a lighter application since they will hold less color and q-tips and makeup applicators will apply more color since they hold more.
If you have the medium to softer variety, they can be used the same as chalks. You'll get a wider range of colors with pastels. Note: there are oil pastels vs. pastels, you would want just the regular pastels. The harder pastels can be used to, but take a little more effort when using an applicator to pick up color. The best way is to scrape the pastel with a knife to remove color then pick it up. Some pastels are water soluble and can be used to create beautiful backgrounds.
Are pastels in pencil form. These are wonderful to use and the color range is wide. You would use them as you would chalks and pastels, but you have more control at times since you can sharpen the pencil. You can adjust how much color you're adding by the pressure applied to the paper. They offer the ability to work in more detail and smaller areas. If you are looking to invest in pastels, look into getting a good set of pastel pencils.
I use either a gum eraser or a white art eraser. Just my preference.
For most chalk/pastel colored images, a zap with a fixative is a good idea for longevity. Especially on smooth papers where the chalks will have more of a tendancy to wipe away. I use either krylon or blair fixatives, I don't recommend hairspray. You're creating a piece of artwork, treat it as such.
Basics:
The differences between decorator chalks and pastels/pastel pencils are the binding agents and pigments. Good quality pencils and pastels will have high pigment concentration and quality. But for most work, chalks really do a wonderful job.
With chalks, pastels and pastel pencils, their key is their ability to be layered to create additional colors and depth. Typically you would want to start with the lightest color first and add darker colors as you progress or as needed. Work highlights first then work towards the darker shadows. Think about your light direction (if doing a piece that you want to add a little realism too). If the light comes from the top right, the right side is where you would highlight. This is a basic painting and art technique and much information can be found on the internet.
Also note that highlights are not necessarily white nor shadows black. Look at things around your house and think about what color is the highlight? Yellow, blue, green? And the shadows, are they more brown, blue-black, etc. I use purple and dark blue for shadows quite a bit mixed with other colors too. Use your imagination, you can create some great looking Picasso and Monet type of pieces depending on your color usage and focal point.
Blending:You can use your finger, a clean applicator or tissue. Whatever works for the type of image and area you want to blend colors. Layer the colors as you apply them to blend them too.
Techniques:
Blender pen: You can use a blender pen to pick up color from the chalks to apply to your image or you can color your image and use the blender pen to extend the color to another areas, to increase the color in the area you're in. Be careful with some papers as a very wet blender pen will eventually tear the surface of the paper and create pills (like on a sweater). But a light tough and letting the image dry if it becomes too wet will help.
Reverse stamping:Ink up a reverse stamp (they look like large shadow stamps) and take a cotton ball or medium, soft paintbrush and apply color to the stamp. A versamark pad works very well since it does not get too wet and has a great, sticky application; the chalks will adhere well. After "chalking" up the stamp, I usually tap the versamark pad on again and sometimes add more chalk. Then you can stamp onto your paper. You can also stamp additional images onto the stamp after the chalks are applied with whatever color ink goes with your chalk theme. I would recommend pigment inks for the additional images. A neat idea is to use orange, yellow, red with a hint of the bright pink and then stamp leaves in medium greens and stamp onto white cardstock. Looks very pretty. Also, use sunset or daybreak color themes and then take a simple tree landscape or branch in dark brown.
Versamark:Stamp your image with a versamark pad (if you don't have one, I would recommend getting one, they are quite versatile pads to have as you can use them for additional techniques). Using a small, soft paintbrush or cotton ball, apply the color to the image outline. You can follow the color scheme of the image (like using greens for a leaf, etc) or be wild and use the complimentary colors of what the image theme would be (like using oranges for a leaf with some pink and maybe a hint of blue or green). It's up to you. The extra chalk dust can be wiped away gently using a tissue, dryer sheet, etc. What can happen when using the versamark method is that color will get where you don't want it and it can stain the paper (more obvious on white). You can usually erase most fly-away chalk though. You wil notice this more with the darker colors, especially reds and blues.
Sticky Embossing Powder:Stamp image and apply heat 'n stick embossing powder. Heat the embossing powder from underneat so it doesn't get too hot. Apply chalks as you would when doing the versamark technique.
Chalks and other mediums:You can use chalks with just about any other medium, although I wouldn't recommend using it with acrylic paints or oil paints due to the opaque quality of these paints. But watercolors, watercolor pencils and crayons, even radiant pearls can be enhanced with chalks. I typically use the chalks for shadowing and highlights with watercolored images. You can use pearl ex powders (or any mica powder) over your chalked image to create sparkle and iridescent shine. I would spray with a fixative first before applying mica powders if you're using a blender pen to add them. You don't want to remove color by accident.
Pastels and backgrounds:Water soluble pastels can make beautiful, monet-type of backgrounds. Watercolor paper works best for this especially if you're planning on doing a lot of blending. You don't want to destroy the paper surface. Just add the colors you like and blend away. Add more water or color as you like, it's a very individual technique.