Getting along with a son-in-law may be easy or difficult depending on your personalities. No matter whether you think that he is the "best thing since sliced bread" or you wish your daughter had chosen someone else, it is important to get along for your daughter's sake and the sake of family harmony.
Say kind things to him
You want to be nice to your son-in-law. Ask how he is doing when he comes. Act like you are truly interested. When he is over your house, then offer things you know he likes such as a certain drink.
Show interest in his interests
Many men love to talk about their own interests. It may be about their jobs, a television show or something else. Ask them about these subjects. Listen while they talk and show them that you care about what they have to say.
Stay away from touchy subjects
There may be a particular topic on which you do not agree. It may be about politics, a sports team or something else. Do not make it your mission to convert him to your way of thinking. You should not bring up a subject, which will just make everyone uncomfortable.
If your son-in-law needs a favor such as someone to drive him to the airport then offer to do it. If they need a sitter, then be there. Try to lend a helping hand, and he may think more favorably of you.
Do not enmesh yourself between your daughter and her husband
Your son-in-law may get frustrated if he feels like you jump into every argument or fight between him and your daughter. She may be your daughter, but she is his wife. Obviously if it is something serious such as if there is physical violence or your daughter truly needs your help then you can get in, but it generally is not your place to go in otherwise.
You will also want to try to avoid meddling in their lives too much in general. Of course many couples like the advice and information from their parents, and that is fine. However, many parents push themselves into the lives of their daughter and son-in-law¸ and he may resent that. Especially be careful about telling them how to raise their kids.
You want to have as positive a relationship with your son-in-law as possible. The above tips can help you get along.