defo tone and moisturise before foundation is applied. and as mention exfoliate at least twice a week.
there are 3 types of skin, oily, combination and dry, 9/10 people have combination skin (oily and dry), so if your oily, avoid moisturising as much and get some foundation that is specifically for your type of skin, if you aint sure which type you are, a beautician will be able to help.
boot, superdrug etc, all have makeup made especially for people with dry/oily skin etc.
Hope this helps....(that was the beautician in me coming out ) sorry lol x