Of the various forms of art, I recommend the still life as the best learning tool. When I started out I first studied the still life paintings of Chardin. I copied paintings by Chardin and Cezanne, among others.
1973 Richard Perry oil on canvas from Chardin composition
The advantages of still life painting are:
You can take your time (until the fruit rots).
Unlike a landscape you can easily rearrange the composition.
I recommend using a lazy Susan so you can spin your objects around to get new views. This allows for randomness - a great tool to progress in art. (I read that one of the Impressionists, it may have been Renoir, painstakingly set up a flower still life in class, only to instruct the class to paint if from the back.