Making first hat without pattern

I'm trying to make my first hat without a pattern. I've done 3 years already so feel confident I can get it done, but I'm doing it differently. First I don't want to fold it up at the bottom and I want that rim to be seed stitch in two colors. The rest is simple stockenette and then decreases. My question is are there anything I need to consider? I'm assuming is the cast on fits my head the rest of it will. I did a measurement of my older hats to see how many rows is needed before decreases since I'm not doing the fold. I'm just tired of ribbing. I want something different.