The absolute worst thing you can do when picking an Agent to sell your property is go with a friend or some one you went to school with thinking that they will do you a good turn.... They won't and it will still be on the market 2 months from now.
Also; lower commissions and fees are to be avoided like the plague, as lower fees and commissions mean lesser marketing strategies.
Pick an Agency with a bigger team of Agents. (I.e. don't pick an Agency that has 2 Agents only) As some of these agencies will have over 20 properties on their books. After all, what sort of job are two Agents running around 20 open houses on any given Saturday going to do when it comes to selling your property?
Have a look on realestate.com.au and domain.com.au at the agents who are selling properties in your area, click on a few of the listings of those agents and have a look at their sales strategy. Put yourself in the buyers shoes and ask yourself; as a buyer, which listings are attractive (I.e. are the photos of the property good, does it include a floor plan? Do they have a video of the property?) For example, there's an excellent agent in Sydney's Hills area called; Harcourts. With almost every property they sell, they make a short video outlining the features if the property. They're really well done, and as a result, Harcourt's open houses usually have 10 + groups going through them on any given Saturday.
Also have a look at the sold properties in the last month on reslestate.com.au. Which agent has sold more properties? ( Although, choosing the agent on sales figures alone is sometimes not the best policy either)..... The Agents we went with had the highest sales in our area for January and Febrary 2013. However there were only two Agents working for this Agency. As they both had 20 + Open Houses on a given Saturday between the two of them, they really didn't do our property any justice.