Keep your skin as clean as possible but don't overdo chemicals by using loads of harsh products, your skin needs some oils. There are loads of products out there for oily T Zones from cleaners, toners, face washes, moisturisers and makeup but you don't want to end up clogging and blocking your pores and making things worse.
That said, using the wrong kind of products may not help either and could make things worse. What do you use now?
A prescription facial by a decent beautician could help get you some advice about the best way to care for your skin.
For general skin health, it's a lot about how you treat your body, what you eat, fresh air, enough sleep, lots of water.... If you are younger it could be something hormone related, many teenagers and young adults get greasy skin and spots. If you are getting too warm or work in any kind of hot or humid environment then make sure you keep as cool as possible and get fresh air and let your skin breathe.
Are you male or female and how old are you? Could help in advice.
Papier poudre could come in useful in "emergencies" - this kind of thing.
http://www.amazon.com/Papier-Poudre-Oil-Blotting-Papers/dp/B000AV1E8G