No one enters their marriage expecting the relationship to end in divorce. Unfortunately almost half of all marriages do eventually end in divorce. The decision to file should come only after you have explored all other avenues including counseling.
Once you know divorce is inevitable then your first step should be to speak to an experienced matrimonial attorney. I have been practicing for since 1985 and my practice has always been primarily in this area.
While I appreciate that human nature will bring you to research on the Internet and speak to family or friends who have been divorced I strongly suggest against it. Laws are different in every state so the Internet will not always be accurate. Friends and family are also not the best source since most divorces are settled between the Parties and each case is very fact sensitive.
I offer a free initial consultation when I explain the legal process and your rights so feel free to call me at 732-608-9342.