Hello, before I get started I just want to say that not everyone is going to agree with what im saying here, please leave your opinions or how you do it differently in comments.
This guide will cover how to improve your gearscore and at the same time make gold to buy Cold weather flying or fast flying. The first thing I do when I get to level 80 is start doing the Sons of Hodir questline, remember that every high level quest you do when you are level 80 you get around 100 gold. Search on google how to do Sons of Hodir reputation, it takes roughly 1 hour and you can get some decent items from it. When you get revered with Sons of Hodir you should have at least 1000gold and thats enough to get yourself Cold Weather flying. Even if you dont get any items from that reputation it still has some nice enchants that you will probably need. After that you can either look to do Kirin Tor reputatation, Argent Crusade, Ebon Hold or Wyrmnest Temple. Just check on internet what each quatermaster has to offer, and if thats what you need. Just by doing these reputations you can get around 3k gs, which still isnt enough to do heroic dungeons. Always have your eye on global chat if someone is doing heroic walkins because thats also a good way, but hard. If you want to create your own party for hc walk ins look to get a strong tank. BOEs from raids are still going for insane price, and since Ulduar is coming out in a day, it wouldnt be worth for you to buy them and just change them when Ulduar comes out. Try also to get into a decent guild and they might even bring you in a raid and boost your gearscore significantly. Best professions in my opinion to make money are gathering professions such as mining and herbalism, but you can also make a lot of money with alchemy and herbalism if you know what to do because everyone needs potions. Mining and herbalism is just plain and simple, mine the ores and sell them same thing is for herbalism
Thats all from me for now, if you do things any different please put it in the comments so we can discuss it.