Usually this happens the day you have something big going on or right when mother nature decides to give you your monthly visit. Here is how you show mother nature you can deal.
1. Use a primer. This will give your makeup something to hold onto when trying to cover an oily blemish.
2. Try to cover your blemish with foundation. Apply as you normally would. If you can still see the redness from your blemish move on to the next step.
3. Apply concealer. Do not use your finger for this step. Your finger will heat up the concealer and make it too soft to apply correctly. Use a concealer brush to help you get into all of the little nook and cranny's.
4. Cover with a translucent mattifying powder. This will set everything in place while providing additional oil control.
That's it. Now you are good to go for the day.