Making your own line of cosmetics for sale is very unique and a novelty. Of course there is always the competition from the major brands, there is always room for a niche product or design. Chances are if you have a unique angle on a particular idea, you can market it with great success. Getting started goes one step beyond the recipe. Start thinking about a brand name that you can begin promoting and then some packaging sources. Having these out of the way first allows you to focus on the sample recipes and mixing of the product. A fair amount of research will have to be done first to determine what people are interested in buying. With the wellness craze and the demand for more wholesome products, this could work well for you.
If you have never made any cosmetics, going to the forum is going to help you the most. Forums will have tons of recipes and help from people that have made all sorts of products on their own. You can find information such as:
How to make lipsticks
How to get certain colors
wholesale clients
where to buy lipstick molds
where to find starter kits
suntan lotion formulas
surfactants
sterilization techniques
eyeliner
mascera
foundation
Obviousely the key is to read read read, and then read some more.