Always ask for a faxed or an emailed itinerary. You may end up with a ticket requiring you to overnight enroute to your final destination and get there a day after you expect to. Always ask how long you have to actually purchase your ticket. Generally you have anywhere from one day to seven days. Make sure your price includes all applicable taxes and any other charges that may apply.
Many countries have entry and departure taxes payable at the airport upon arrival or departure.
Always ask if you can purchase an electronic ticket whenever possible to avoid hassles with lost or destroyed documents. Inability of a travel agent to answer any of these questions should raise a red flag. YOU ARE ultimately responsible for ensuring you are getting exactly what you need. Use your judgement. If something does not sound right, there is a possibility it isn't.