Don't worry. These can be roughs.
Like other things, you will probably just need to practice different styles of lettering in different media until you find what works for you. Maybe you could buy a calligraphy book and scan fonts you like. Then with lasso tool you can create 26 custom letter brushes that you could then make into different colors and sizes. I'm just talking out of my ass here, because I know my own lettering is nothing to get excited about.