Tips checkers
Be aggressive, you are more likely to win. Playing to the board sides are safer though without reward. Forward- always forward, it's alright to lose pieces as long as you take the opponent's, save your kings. Balance your position, good practice is to have as many pieces on your right half of the board as on the left half. If you see a big imbalance in your opponents position you can try to empty the emptier half even more and advance to a king. Safety in numbers, don't leave your pieces alone, move them one after another to protect them. Having lots of holes between your pieces opens you up combinations. Protect your rear, such that the opponent cannot do a combination to your last row, protect your forward pieces. Sacrifice when needed. Draw out your opponent so you can get 2-1 trades the following turn, don't expose your kings without reward. Each king you get is a huge bonus, try to get as many as possible and don't waste them, sacrificing several (generally up to 2) pieces for a king can be alright. Don't forget to block your opponent when possible, you make not only that piece vulnerable but fail to protect it with a counter and give your opponent the chance to take multiple of your pieces in one turn.
International draughts
Keep your pieces together, don't make big holes. See if there are any combinations possible.
Pieces in the center can move multiple directions, while pieces at the border are safer for combinations they are more limited in their movements.