There is a really good reason why you should combine two Apps together rather than stick with one for drawing and then start another when you paint.
This is because the information you have gained, the form, the tone (shading) using the Drawing App (ASKetch) should never be lost. Here is my drawing using ASKetch (left).
There is so much information in my drawing from life (not from a photograph). If I use this ASKetch drawing as the basis for my still life painting, it will prime me to see the structure and depth of the objects and I can go on to enhance them with colour and tone. Most painting Apps give you fine linear tools to draw with: these are more difficult to use when you are starting to learn to draw and paint on your screen!
In Artrage (left) you can see the photo I took, and the dark and light tones of my ASKetch drawing from life. The pepper is being worked in reds/oranges/light yellows. The highlight on the top left of the pepper, which was carefully modeled in the drawing, indicates the direction of the light. I am using a square brush and oil paint.
Although incomplete, the painting “Pepper and Pear” ( right ) demonstrates more of the use of colour, tone and volume. You could almost grasp the pear. At the same time I have enjoyed the fluid “feel” of the objects using my brush.
To learn how to use the two Apps together by taking the ASKetch drawing in to Artrage go to HERE. It is simply and clearly explained. This is from the INSTRUCTIONS menu on the website (see above).
At one point I took the Artrage painting into Procreate because there is a particular brush I like. It gave me the texture of the pear. Experiment with Apps only when you have got the basics worked out!