The culture of a GP might not seem that important to the average person, but think about the things you might see them for in the future, and how their beliefs could affect you. Some GPs, for example, do not advise on contraception or abortion for cultural and religious reasons. They'll refer you to another GP or family planning clinic, but it's much easier on you (both mentally and physically) if you don't have to go elsewhere.
This brings up one of the most important considerations in finding the right GP. The ability to talk to them. A GP is no use to you if you feel embarrassed in their company. General practitioners are not just there to prescribe drugs for the flu; they're your first point of contact in the health industry for all-over health, and that includes what's going on in your head.
Say you're having trouble sleeping, for example. A good GP won't just give you sleeping pills based on that admission alone. He or she will want you to talk about what's going on in your personal life, and what is keeping you up at night. You will need to feel comfortable revealing deeply intimate details about your life, and you can't do that if you don't trust them. The same goes if you're experiencing anxiety, depression, anger, or anything else that's going on upstairs.
Also remember, your GP is a person who will probably inspect your privates at some point. You need to be comfortable in that respect as well.
Logistical considerations will also come into play. You don't want to be driving an hour to see your favourite doc. You'll also want to consider how easy it is to get an appointment. Can you call up on the day? Will you need to leave work, or does the surgery offer late nights and weekends? Does it have parking or public transport access? Think about all these things before registering.
On that topic, don't register with a new surgery before meeting the GP. Make an appointment first so you can assess the interpersonal dynamic between the two of you. If you don't get on, you don't want to have to re-register all over again somewhere else (your files will take several weeks to be transferred).
This will inevitably cost you more for one visit as a non-registered patient, and you might need to try out a couple of GPs (as necessary based on your health needs) to find the right fit.
On the topic of costs, make sure you know how much it costs for a registered-patient visit. The state-subsidy on primary healthcare only goes so far, and each surgery will have unique surcharges - for community clinics fees should be around $17.50 for a 15-minute appointment; medical centres that offer a range of services (especially those in CBD areas) can charge $60 or more.
With all of these considerations, you're probably wondering by now how you actually find out all this information. You have to ask. Ask friends and family who their GP is, and get the lowdown on whether they could be right for you. Take to Google if you're looking for someone within your culture, as most surgeries have websites and will list these kinds of things. And don't be afraid to phone up the surgery itself, and ask about the doctors on staff, pricing, and appointment availability.
A GP is more than just a health professional with a file on your medical history. It's a person with whom you should have a healthy relationship, so you can enjoy a healthy life. Make sure you get the right one for your individual needs.