You know you called your spouse to tell her that your son was failing in English class, but you have no proof. I have heard this story all too many times. One of the very first things I tell a prospective client is that you need a good paper trail. What does this mean? This means that you should back up everything you say on the phone in writing. In this day of advanced technology, nearly everyone uses text messages or e-mail. If you have a telephone conversation, document it by confirming by text, e-mail, or certified mail.
Be organized. If you know you are dealing with a difficult party, make sure you have all your documents together and in order. Do not wait until you are before a Judge to get your wrinkled documents bunched up out on the table. Have copies for everyone, in folders, and easily accessible. Know what you are saying, make your point, and back it up with documents.
Being prepared and having a well organized paper trail can really make your case.