It is important use a 70% or 90% volume alcohol that you can find at a local pharmacy.
For lipstick: Fill alcohol lid with alcohol, and dip the top part of the lipstick into the alcohol. Use a tissue to wipe off the excess alcohol on the lipstick, and its ready to use. You can throw away any leftover alcohol.
For eyeliner pencil: Sharpen the eyeliner with a sharpener. Dip the tip in alcohol, then wipe off the excess alcohol.
For cream concealers, blushes or cake eyeliners: Do not dip brush directly in them. Use a spatula or somehow scoop some out of the container onto a different surface. If it has already been used directly from the container wipe down the top surfaces gently with an alcohol damp tissue.
For dry products (powder eyeshadow or blush): They do not really grow bacteria, but you can wipe down the top layer with a dry tissue or scrape it off.
For liquid makeup: There is no way to clean. If it starts to smell funny, change color, or irritate, there might be a problem. Then, just throw it away.
Do not share these types of makeup. Also, pay attention to the expiration date.
Following these steps will completely clean all your products, and keep them germ free.