One of the best websites for new pickleball players is the tips pages from the USAPA. Here is the link:
Strategies for doubles play can be found here:
More strategies: Video series
Some words of wisdom:
"No matter where you are on the court, if you don't know what to do, hitting the ball in the kitchen is never wrong, it is always a great choice and never get you in trouble". - Steve Dawson, former US Open, Canadian Open, and World Pickleball Champion.
Here is a great article from Pickleballmagazine.com on when to attack. Green, Yellow, or Red?