Hi wisewomen,
i also have a tendency for an oily t-zone and the odd break out (despite being in my early 20s).
i've recently tried Clinique superbalanced foundation, which is quite good, because as you've learnt, some foundations for oily skin can dry out the areas on your face where you don't have a problem with oil, superbalance does exactly what it says on the tin, it balances out your complexion. I used to use a foundation years ago from Neutragena that was reallly good too for oily skin and break outs.
i agree with petal flower, definately use a foundation brush. to add to petals merits of using the brush, it also makes putting on foundation quite quick. i've tried a few foundation brushes (quite expensive ones), but one from Superdrug for �3ish works exactly the same. also use a concealer bruch to cover up imperfections, that way you won't transfer oil from your fingers to spots.
before you apply makeup exfoliate, cleanse and moisturise. make sure your moisturiser is oil free and is aimed at combatting break outs. by changing your moisturizer you may find that your foundation works better on your skin.