There are lots of software painting and drawing tools/apps out there - many are free and some cost. I took a class last year and found it very helpful to educate myself on all the options. This piece was done in ArtRage on my iPad.
I dig the variety of features - tools and colors. There are pencils, water color , oils, chalk, pens and more! You can change the sizes, width, and opacity. It's easy to blend and get similar results to paper and paint. It also has a nice help button. The best part - no clean up!!
Take care and STAY POSITIVE!