Ngdawg is right, acne cleansers make things worse.
There's two kinds of acne, ones caused by bacterial infections and ones caused by clogged pores. Clogged pores often become bacterial infections because the body can't keep them clean.
Your pores don't make oil, they make sebum, which is a mix of oil and dead skin cell "gunk". It's the gunk that clogs your pores, not the oil. Acne problems happen when too much "gunk" is produced for your body to deal with. Delicate and sensitive skin is more prone to irritation from sebum and more likely to get zits, especially the bacterial kind (cystic acne and inflamed whiteheads). Tougher skin, like that on your nose, is more resistant to the bacterial infection but will get blackheads in the even of excess sebum.
Stripping oil from your skin causes your pores to produce more sebum! Oil is not the enemy here. Neither is the "large pore" issue; trying to reduce your pore size with astringents can irritate pores and make them less capable of simply expressing the sebum and more likely to clog.
There are three very good ways to prevent and cope with acne.
The first is to use the right cleanser and moisturizer.
The best cleanser is a very gentle soap, such as Nutrogena, that is non-comodogenic (means it won't clog pores). Don't use a harsh detergent meant for acne, it's too much. This removes surface dirt and excess oil.
Moisturizing is vital because if your skin is dry it will only make more sebum. Choose a moisturizer that is non-comodogenic and non-medicated; beyond that, it doesn't really matter, just pick one that makes your skin feel comfortable and supple. I like pretty much anything made by Aveeno as it's all very soothing and gentle. Always apply right after washing; if you apply it later, it will sit on top of your skin and block pores.
The second step is to deal with any sebum clogging your pores.
You can physically remove the sebum from your pores using a clay mask. Anything that has kaolin clay will draw oil and gunk directly out of your pores. Choose a gentle one, without medications, and you can use it three times a week. You can also leave it on longer than it says on the package and it won't harm you at all, as long as it's non-medicated. My favorite is the Neem mask they sell at Bath and Body Works. It looks expensive but lasts a really long time. You can apply a glob of clay directly onto a zit, let it dry, and put a band-aid on it, and wear that overnight; my mother swears by this. But it's better to prevent blackheads by applying it regularly and preventing build-up.
Finally, if you get a zit, how you deal with it is important. Blackheads should be left alone or removed with keolin clay, because trying to squeeze them will cause them to turn into infected zits (whiteheads) if you aren't able to completely remove the clog.
Any inflamed zit should be carefully observed. There is an optimal point to deal with a zit. If it has not developed a very clear white head, leave it alone! Trying to squeeze it before it's ready can cause a cystic zit--that's a deep, painful zit that can't be squeezed and may scar.
Once the zit has developed a clear whitehead and a slightly pointed shape (instead of being mostly flat or rounded) the clog is close enough to the surface to remove without causing damage. It is very important to remove ALL of the infection.
Use a pin or fine tweezers to very gently break the skin over the whitehead, which is like a blister so this should not hurt. This is so you do not have to use as much force when squeezing. It might "pop", and you might think you're done, but always give another gentle squeeze to be thorough. If you leave any infection inside it will only get worse and more painful and might scar.
Once you're sure the pore is completely clean (if it bleeds, it's clean--don't be alarmed, it's your body attacking the infection), disinfect the outside area with something like Bactine or rubbing alchocol to prevent the spread of infection. If it's bleeding, gently dab at it with a tissue to prevent a scab forming (large scabs slow healing and look ugly!). The zit should be gone by the next morning. If it's still red and angry, the infection is still there and you should start the watching and waiting process over again.
OK! So, who's grossed out now?
Seriously, all of this stuff works. Prevention is key, but when you do break out, I can't stress enough the importance of leaving a zit alone until it's ready. Mess with it too early and you'll be sorry!