Need advice(s) for styling existing ionic app

Hi everyone.
I have built a couple of slick Ionic apps for a company I currently work for and they work fine. I use pretty much all the default styles of components (buttons, cards, lists, etc…) and it seems my app now just need to be custom “styled” a bit. My problem is that I am not that great at CSS. I know I could use SASS and customize the scss/ file, but I wish there was a guide somewhere which could give me advices and examples. I have tried to follow the formula here:
but the result isn’t that great and I reverted to the default styles. Maybe I should start learning SASS? Is it worth the hassle? What are you guys experience on this subject?