Wall molding is used along the top and bottoms of walls to improve appearance along the floor and ceiling by adding a subtle attractiveness to the transition area between the wall and where it meets the floor or ceiling. Molding can be bought in long pieces with any number of designs cut into it, and is relatively easy to install. The most important thing to consider and plan ahead for is the types of adhesive materials you'll need to properly and securely install any type of molding.
When applying the molding to the wall, you will need to secure it on with common wall adhesive. Be sure to get a urethane-based, heavy-duty wall or wood glue. This will typically come in a tube similar to caulk and can be applied in long strips using a caulking gun. You will need enough to make several passes up and down the wall where you want to install the molding. Strength of the adhesive should not be a major concern, as any commercially available wall glue will be plenty strong enough to hold molding to the wall material.
While not so much an adhesive in the traditional sense of the word, standard carpenters nails are still an integral part of securing the molding to the wall. You will need to find the right balance between nail length and thickness. The nails need to be long enough to go through the molding and securely into the wall, yet still thin enough to be easily painted over once the molding is installed. The molding will be placed onto the wall over the traditional adhesive and then further secured using the nails on every other wall stud.
Caulk plays a more superficial role than either the wall glue or the nails in the installation of molding. Use any readily available brand of standard caulk in conjunction with a caulking gun to apply a thin line along any joints in the molding. Corners and seams where two pieces come together should get a light application of caulk to hide the crack. Any excess should be wiped away before painting to avoid imperfections and bumps along the seams.