I find when i use just the liquid cover up my skin looks really greasy and oily
my skin is oily itself yea.
+ i have acne that's the main reason i use makeup to hide it

and your a guy...?

yes and your supose to.

yes, in fact that will help your makeup stay on longer and give your face a soft matte finish
keep that powder or an oil control powder with u when u go out and when u find your face to be getting a shine, blot it with a tissue a little; or blotting paper and then lightly dust some powder on to re-create your matte look

You should be using a foundation that is made specifically for oily to combination skin. I am a Mary Kay Beauty Consultant and we sell foundation for oily to combination skin as well as normal to dry skin. We also have a very reasonable acne treatment gel ($7 tube) as well as a blemish control toner. Once you get your face cleared up, you won't need to worry about hiding anything....let your natural beauty shine through.