I agree with lipshock's recommendations. Estee Lauder Double Wear Extend is perfect for more oily/combo skin. If you have dry skin, moisturize, moisturize, moisturize before you apply. I love Mac Studio Fix Fluid for more normal to dry skin. And if you have great skin already and just need some evening out, Laura Mercier's tinited moisturizers leave a flawless finish.
Also, invest in a great brush for foundation application, Mac's 187 is PERFECT for this. And never glob on the foundation, even if you feel you need full coverage. Rather, apply your foundation in thin layers to build coverage and set with a fine milled loose powder if needed.
I also recommmend using a primer to create a smooth base for your foundation and concealers and highlighters to spot treat specific blemishes, etc. Lastly, you MUST moisturizer and take care of your skin to achieve a flawless finish with your foundation!!!! Even if you have oily skin, it is so important!!!