The way dive trips are organised and run is also important. A chaotic, badsly organised dive trip is no fun for anyone and does little to inspire confidence. A well-run dive trip on the other hand can make all the difference to your day.
What are the dive centres boats like? A small, simple boat is absolutely fine if the dive site is close, but if you have to travel further, you'll be spending a reasonable amount of time on the boat so it's important to be comfortable. And what are the maximum number of divers per trip? Thirty divers on a large boat is no problem, but on a speedboat it's far from ideal.
The size of your dive group is also very important. No matter how good your guide or instructor is, the more people they have to look after, the less time they will have to pay attention to you. It's also worth asking if the dive centre visit a variety of dive sites. Everybody likes to see new places and visiting a variety of sites can really enhance your experience.
Lastly, researching a dive centre's repuation is a great way of deciding if they are right for you. Divers love to talk and there are plenty of websites and forums with all sorts of useful information, comments & experiences. It's worth remembering that even the best dive centres have bad days and occasionally cistomers leave unhappy, but if the majority of people have good experiences and are happy to recommend a dive centre to others, chances are they are doing a good job.
So by following these tips & making a careful decision, the next time you plan to go diving, you can be sure you pick a great dive centre as well as a great place to dive.