Don't waste your time with information you can learn on your own!!! Spend some time researching what divorce is like in your state. Each state is different, and unless you are a complete moron you should be able to read a few websites about your state & get a sense of what is or isn't going to apply to you. You can easily save a 20 minute conversation right there if you already know some of this:
How is custody typically approached?
How are marital/pre-marital assets normally divided?
What are the standards and/or advantages to filing for fault divorce versus no-fault?
What is the ballpark timeline for divorce in your state?
When you go there bring:
Pay stubs for both of you for the past year or two
Last three years of tax returns
A print-out of your assets - home, car(s), savings & investment accounts, and so on
A print-out of your liabilities - home loan, car loan(s), credit cards
Any evidence you want lawyer to consider using as leverage should the need arise (phone logs, emails, texts, photos)
Do not waste your $$$ getting into an emotional crying jag/counseling session with a lawyer. Emotions are expected to run high, particularly with the first consult, but the more time you waste bitching about what a whore your STBX is, the less time you'll have to talk about the business of the divorce.
Schedule time afterwards to decompress. Ask a friend if you can socialize after, or go do something you love to do. I've learned the hard way that it's really important to decompress and breathe after something as Majorly Big as meeting with a divorce lawyer.