If you need a bit of inspiration from master painters, but don't have any museums or art books handy, check out this facebook group: Hi Resolution Paintings and Close Ups!
People are posting high resolution paintings of all sorts, (portraits, landscapes, still life...etc). Some of them are so detailed you can see each individual stroke of paint! I like to check the page at least once a week as there is plenty of new work to see. ~ Enjoy!