Domenico DeMarco might be the best pizzaiolo alive:
Just watching that my pizzas improved considerably: parmesan, fresh basil and extra virgin olive oil after baking the pizza. He puts some oil before baking and I think it's a good thing, but most people disagree on that.
Frozen pizzas have two problems:
- Bad crust You can improve it baking in a pizza stone or, if that's not an option, putting some olive oil in the tray you put the pizza.
- Bad ingredients It's always a matter of taste, I suggest keeping it simple. Mozzarella and any other cheese that melts should help.
By the way, making pizza at home, from scratch, couldn't be cheaper. Believe it or not, you're overpaying for the frozen stuff.
Also, you are grating your parmesan, right?