What is the best Jane Austen novel for a beginner.?

While "Pride and Prejudice" might be her best known work "Northanger Abbey" is not a difficult read.  It is also one of her shorter stories and based on the content it most likely is the first novel she wrote. (That doesn't mean published) .  

My favourite has always been "Emma". A kind but "entitled" rich girl seeks a kind but not so superior husband for her dim friend, and finds out that she can't command anyone's love life, not even her own.

I found Pride and Prejudice very easy, but maybe keep a copy of the Sparknotes book beside you as you read - that might assist you with any passages or words you'd find difficult.