Here is a word I mess up on a lot. But maybe this idea will help.

Bad: familer

Good familiar

One way to help on this word is to look for letters that are familiar. How do you determine that, by seeing letters more than once and they look fAmIlIAr.  Two As and two Is. So fAmIlIAR.

An alternative mind device might be that if you are famiLIAR with a certain subject and someone else tries to be a LIAR with information on the topic you know, you can catch them.

If you have a more successful way to remember how to this word correctly, please feel free to share it.