I'd say to check out the materials in the program and check out the page with the free ones -- they can be really and truly helpful and save you lots of time in workflow!
It's easy to get overwhelmed, and sometimes you just have to take a few breaths, take a step or two back, and just assess the situation. Sometimes you have to take a little time away, but not too much time. You don't want to lose the spark of the story at the very beginning.
I'd say, don't be too harsh on yourself. Let yourself experiment and do things a little wildly. See what works and what doesn't. Use plenty of layers! You can always adjust the look later or make the layer invisible and replace it with something else if you don't like it. Use the resources at your disposal to the best of what they offer. 
If you need any help with Clip Studio Paint, I'd be happy to help however I can, if I can!