Dominoes is a relatively simple game, however there are a few general dominoes strategies to keep in mind when playing.
Play doubles early
Get rid of your doubles as soon as possible. It's easy to get stuck with doubles since you don't have as many opportunities to play them.
Play high-value dominoes early
Try to play your high value dominoes as soon as possible. That way, even if your opponent wins the round, hopefully they won't score too many points.
Keep your options open
Try to keep at least one of every number in your hand for as long as you can. This will help keep you from getting stuck in an unplayable position.
Identify your opponent's weaknesses
When your opponent has to pass or draw from the boneyard, make a mental note of which number or numbers they don't have. You can use this information to try to block them later on.