One of the first questions people ask when taking the step from considering a divorce or separation to speaking to an attorney: is what information do I need to gather? In order to provide you the best information possible, it is helpful to have some basic information in order to tailor the advice to your specific circumstances.
The information that is most helpful is financial. If you have the most recently filed tax return, with W2s; recent retirement, bank and credit card statements, that can help flesh out your financial picture and begin a discussion about how those assets/debts can mold your case. Knowing the incomes of the parties will permit a more informed discussion about child support and spousal support.
In the long term there are many more financial documents that will need to be gathered and discussed, but the short list will be helpful to get the ball rolling and hopefully provide you, the client, with relevant information to better guide your decisions.