Tips for wavy/slightly frizzy hair

So I've been straightening my hair for over 10 years. Over a year ago my GHD broke and my friend lent me her's as her hair was short and she stopped using it. She finally asked for it back a few days ago and I still haven't bothered trying to get mine fixed yet!

I've always just blow-dried my hair roughly and then straightened it straight away. I did this the other day and intended to straighten straight away but I started doing some housework. When I went back to start straightening it, it had gone from a big frizzy, slightly straight mess, to lovely natural (but still slightly frizzy) waves. It's the way I've always wanted my hair to look but I was never able to achieve it so always just straightened. It's straight enough on top and then has lovely bouncy curls at the bottom. I was delighted with it, and my boyfriend and friends thought it was gorgeous. I'm so happy that I don't have to be a slave to the hair straighteners any more

Anyway enough of my rambling. I'd really like to know some tips as to how to deal with my hair. I have naturally greasy hair so am wary about using too much product as it just makes my hair go greasy even quicker. Yesterday I put some heat-protecting leave-in conditioner in it before blow drying, and then I put a little Frizz-ease Finishing Creme in when it was done. TBH it didn't make much of a difference from the day before. It still looked nice and I'd be happy wearing it like that for day-to-day, but I'd like it to look sleeker for nights out. I know not to brush it, I just run my fingers through it when it's dried. Can anyone advise on any good products I could use for it?