The SPARC Article Archive has a wide range of material to help you in your divorce and custody situation Even some of the ones you wouldn't think apply to you can be critical to your success. The Pro Se Tips article, for example, tells you how to present yourself and act in front of a judge, and has vital information even if you have an attorney.
Each of the articles in the Articles Section goes into much more detail on these topics than I will here. Many of them have links to other, related articles. The one thing I can guarantee is that you will find useful information in nearly every one of the articles. For example, if you don't think the move-away articles apply to you, you should know that 75% of custodial mothers move away from the noncustodial parent within a few years years of separation. Those are not good odds. Everyone should be following the advice of the "Preparing for a move-away/custody battle" article on a continuing basis. There are hundreds of other articles, too, so make sure you browse the SPARC articles page often.
DOCUMENT! DOCUMENT! DOCUMENT!!!
Your documentation will be the key to your success in court. Your attorney can only work with what you give him. Know now that there is a strong gender bias working against you in any custody matter, so you will have some pretty steep hills to climb. You cannot win a he-says-she-says battle. Your ONLY chance of success is to produce hard, solid evidence of everything you say in court. This article recommends that you keep a journal of everything that happens. I generally recommend that parents read the report "Family Wars, the Alienation of Children" on the PAS Information Archive because it lists some specific behaviors to look for and document.
False accusations are a very common ploy used by women to gain advantage in a divorce or custody situation. Expect it. That is one of the major reasons for the documentation above. The hardest accusations to beat are ones that are based on fact, but blown out of proportion until they have no resemblance to reality. NEVER ADMIT TO ANYTHING without your attorney's approval.
Two thirds of the men getting divorced these days did not want the divorce. This is especially true if there are children involved. The pain and suffering, in my opinion, are even worse than if your family had died. Death is final. With divorce there is a much greater feeling of betrayal, and there are constant reminders and incidents to tear open the wounds time and time again.
Find a clergy or counselor who can listen and assist you in dealing with these emotions. It was 4 years after my divorce before I even realized how badly my ex-wife had psychologically and emotionally abused me, and a counselor finally told me I was suffering from Post Traumatic Stress Disorder. Don't wait that long. You need to heal before you can help your children heal. The domestic abuse of men article above is included to help you recognize this for your own self. Alleging abuse in court is generally not nearly as effective for men as it is for women.
If you know anyone who is just getting started in all of this, please print this out and give it to him.