Speaking of oatmeal, I think right there you're saving money by purchasing this as a breakfast food compared to cereal. The cereals are so expensive. Oatmeal is a lot cheaper and also healthier.
I don't think there are any "do's" and "don'ts" when you're cooking. Aside from the obvious ones that would probably make anyone keel over and want to puke - you should just experiment on your own and have fun - that's what it's all about! I love mixing spices and just experimenting for myself.