How to get rid of greasy hair?

I've tried a bunch of products suggested by other answers to similar questions and they doesn't help. People have told me taking frequent showers is unhealthy and leads to oily hair also, so I've been cutting down on the amount of showers I take to a few times a week. My mother has told me she used to use hand soap to help when she was a teenager (logically a base applied to oil should work) and that helped the first few times and then just didn't so much anymore. In my house we don't have a standard shampoo brand that we use, usually whatever is on sale is purchased (so I've used name brand and store brand and this is still a reoccurring issue.) I just took a shower and blow dried my hair (which I don't normally do, but it usually helps) and afterwards looking in the mirror the hair near the top of my head is oily. I'm sorry this is so long I'm just so fed up with this and really want to find a solution. Any advice would be amazing!