The basic strategy for playing a game of Freecell is:
In the Columns, keep constructing sequences of cards in descending order and alternating colors. Building sequences is just as important as moving cards to the Foundations: sequences are movable between Columns, and can trivially be moved to the Foundations at the end of the game.
Use the Freecells temporarily but free them up again as soon as you can. The more Freecells you have open, the longer the sequences you can move between Columns.
Try to empty a Column temporarily. An empty Column is even more important than an empty Freecell, because it can accept a sequence or help you perform a supermove.
Here’s a great beginner tutorial by Michael Keller.