Boosting HDL
i add ground flax seeds (omega 3s) to my oatmeal in the morning. They cost $3 for a bag at the grocery store and I grind them in my coffee grinder. This seems to be cheaper than buying the oil from a supplement store. (Omega 3s and Omega 6s boost HDL ("good") cholesterol. You can get Omega 3s from flaxseeds, walnuts, salmon, soybeans, halibut)
Reducing LDL
The fiber from Oatmeal, oatbran, etc helps remove LDL cholesterol from the blood. When fat is present in the small intestine, bile is released by the liver in order to make the fat capable to be absorbed by the small intestine for energy. Fiber absorbs some of the bile and carries it out of the body. In order for the liver to make new bile, it uses cholesterol which is bile's building block. So make sure you get enough fiber.
I hope this helps. Good luck