While Tic-Tac-Toe may be the original game about getting pieces in a row, Connect 4 is one of the classic pieces-in-a-row strategy games. Unlike Tic-Tac-Toe, which most people know how to play without losing, Connect 4 involves slightly more strategy.
Here are some quick tips on how to win at Connect 4:
Play in the center column as often as possible.
On the standard 7-column board, any connect-four that is not vertical MUST use one checker from the center column. This means that if you control most of the central column, it will be very difficult for your opponent to get a connect-four.
Look a few moves ahead.
If your opponent can create three in a row with an open, playable space on either side, then you will probably lose. Prevent this ahead of time by paying attention even as soon as your opponent gets two checkers in a row.
Watch out for game-ending spaces.
It will sometimes happen that a certain space on the board would give a connect-four to either you or your opponent, depending on who plays there. If this occurs, then as soon as that space is filled, the game will be over. Because of this, you can safely ignore all spaces above the game-ending space in the same column -- as well as any potential connect-fours that rely on the spaces you are ignoring.
Never play directly below the game-ending space.
This will allow your opponent to play into the space and claim victory. Conversely, you should attempt to force your opponent to play just below the game-ending space, perhaps by setting up a connect-four that forces your opponent to block in the critical space.
Fork your threats whenever possible.
The ideal position is to have two potential connect-fours that need a final checker on two spaces that are on top of each other. This will usually lead to a victory, because you can threaten in the first space. If the opponent fails to block, you win. If the opponent blocks, you play on top to win in the next space. A simple way to set this up is to make a "7" with your checkers, such that finishing the horizontal or diagonal connect-four on the right will be two spaces on top of each other.