Your children will be affected
Unfortunately, in many divorce cases, one or both parties use the children as swords. Spouse end up fighting over custody and/or visitation schedules including holiday and vacation times. An attorney will help both parties stay focused on the big picture. Experienced attorneys are in Court every day either trying these types of issues or conferencing them with Judges to try to find a resolution. They can help negotiate creative settlements that both parties can live with and has minimal impact on the child's schedule. In the event that a settlement cannot be reached, an experienced attorney knows who should be interviewed and what questions to ask at trial to press upon the Judge that it is in your child's best interest for custody to be awarded to you. The decision the Judge makes will have a major impact on your child's future. You don't want to leave that to chance.
You want to save money (and get the best possible outcome)
The top reason for people representing themselves rather than hiring an attorney is that they do not want to pay legal fees. Unfortunately, people that represent themselves often end up making a mess out of their case, especially if their spouse has an attorney. Once they realize that they cannot handle the matter on their own (i.e. they don't know what discovery to ask for, they don't know how to handle the Judge or what arguments to make, they cannot perform a deposition effectively, etc.), they rush to find legal counsel. The attorney then has to work to undo the mess that was made and try to start from scratch and turn things around. This almost always will be more costly than if you had hired counsel at the start.
You want to settle the case
Many people think that attorneys are only necessary if the case is going to go before a Judge and go to trial. This is not the case. Attorneys are no only litigators, they are skilled negotiators. An attorney will be able to effectively discuss the matter with opposing legal counsel, without being emotionally involved, and come up with a creative solution that makes both parties happy. Most spouses going through a divorce cannot do this without the aid of legal counsel, and the matter ends up going before the Court.
You want support (or do not want to pay support)
Spousal support is not a cut and dry issue. New York recently passed a new statute that puts forth a formula for determining temporary spousal support. This formula in and of itself is confusing to those who do not come across it on a daily basis. More importantly, it only applies during the pendency of the divorce action, and is not used for determining support once the divorce is settled or tried and decided. The factors for determining post-judgment support is just as, if not more, confusing than those in the previous statute. An experienced attorney cuts through the legalese and can provide guidance as to how Courts actually rule on this issue, as they see it on a daily basis. They can advise on what is a good settlement proposal and when it is worth it to try the case.
You want to protect your separate property
Separate property is one of the more difficult issues to settle in a divorce. Many people go into the divorce with an attitude that they want to take the other spouse "for everything s/he's got". Unfortunately, even in situations where the spouse knows the property is not marital, they will claim it is marital anyway in an attempt to rattle the other spouse and try to obtain a windfall they are not entitled to. Proving property is separate requires a lot of document review and tracing the chain of custody. This is not something that you want to take on yourself. An experience divorce attorney is trained in this area, and knows what documents to ask for, what questions to ask at a deposition, and what arguments to make to the court to make sure that your property is protected.