It can be a big waste of time for both you and the immigration lawyer if you are not prepared for your first meeting. Being unprepared may also end up costing you money because it will take longer for the lawyer you hire to get up to speed on your legal matter.
Treat your first meeting as a business consultation. Dress well and be prompt. Be polite and courteous. You will want to impress the lawyer, just as he or she will be trying to impress you.