So,first off,we need to start with your skincare regimen.
1)Cleanse-Your cleanser should be gentle,yet fit your skin type.If you suffer from oily skin or whiteheads/blackheads or cysts,use a cleanser with Salicylic Acid,but if you have pimples use a cleanser with Benzoyl Peroxide.
2)Toner-Your toner should ALWAYS be alcohol free,regardless of your skin type or skin concern.Witch hazel is great for those with acne and/or oily skin.You don't have to apply it to the whole face just the affected area.
3)Moisturizer-Yes,even if you have acne,you NEED to moisturize your skin to keep it balanced.Drying it out will only cause more acne.
4)Treatment-Use a topical treatment preferably at night,so if your skin gets irritated it can heal as you sleep.Again,if you have blemishes or blackheads,you'll benefit from Salicylic Acid,but any other type of acne Benzoyl Peroxide.
You HAVETO HAVETO HAVETO have a good skincare routine.Your skin is the canvas,so it HAS TO have a fresh start.
The first step when applying make-up to acne prone skin,is obviously to cleanse your skin.Then moisturize.Moisturizing is a big step.Very important.
Next step.Since you bring up that your foundation is not going on flawlessly,you may need to prime.MAC and Urban Decay have very good primers that last for like ever.Seriously,it takes them a long time to run out.
Next step would be to conceal.contrary to believe,you SHOULD conceal before applying foundation.It looks really tacky if you have concealer marks over your foundation.Use a concealer that caters to your skin needs(blemishes,redness etc).Although if you are using a green concealer,you can use it both before or after.It won't show since all it does it cancel out redness.
Next step,apply a foundation that fits your skin type and skin tone/color.Make sure it matches.Use a sponge or foundation brush to apply it because with hands you'll only spread bacteria and germs.
My recommendations for foundation are Revlon ColorStay or L'Oreal Color Match.When I had acne I relied on Revlon colorstay and my friend who has acne relies on it.It's buildable,and doesn't break you out,plus there's 2 versions,one for oily/combination skin and one for dry/normal skin.I recommend it,but if you like what you already have then so be it.
Then set it with a translucent powder or color powder.I prefer translucent rice powder because it's natural and light and doesn't cake on.
If you do not like foundation,you could try a tint,although a tint may be too light and will not cover well.Laura Mercier also has great foundations and tints,many people with trouble skin use it.
Here's a tutorial for foundation by MichellePhan