One of the best strategies for playing tic-tac-toe includes claiming the center square. This is because the center square is included in three different winning combinations.
This strategy operates on the assumption that you have the first move. If so, mark the center square. Your opponent will either mark a corner or an edge square. If they mark an edge, your next move should be to mark either of the two corners farthest away from their mark. They will have to place their next piece to block your attempt at winning. You should then block their own attempt. This leaves you with two sure ways of winning.
If your opponent marks a corner square, your next move should be to take the opposite corner square. If they place their next move on an edge, you will be left with two opportunities to win. If they place their next move on a corner, the game will end in a tie.
While this strategy will ensure that you never lose, there is always the possibility of tie if your opponent is as well trained as you are. Be wary of making mistakes, because if your opponent is using this foolproof strategy against you, one mistake could cause you to lose.