There are a host of resources online, here are some of the sites that I like to use:

Artcyclopedia – A directory of famous artists – Take a look

Artsy – Discover thousands of contemporary artists – Take a look

Student Art Guide – Aimed at High School/Sixth Form students but it contains some useful drawing and painting exercises that any learner can use – Take a look

BBC – Your Paintings – A great site with access to thousands of famous artists work – Take a look

National Portrait Gallery – A gallery of many famous portrait artists – Take a look

Artist Daily – Useful drawing tutorials for beginners – Take a look

Collage Art – A website dedicated to this area of art – Take a look