Premium is 2500 gold for a month. It gives you increases in experience points and credits earned.
The only premium tank I've seen worth the gold is the German Pz38H735t for 750 gold (5 days worth). It ends up in battles where it belongs, it does well, and it earns well. I'd certainly get one, even before I got on premium, and use it to learn in, as it really is a good little tank, the only real weakness is the slow top speed, and weak acceleration. I've still got mine, and when the game goes live, I'll seriously consider getting one.
You will really want to be on premium when you get to the heavy tanks, as they are expensive to run if the battle doesn't go well for you. I wouldn't wait any longer than right after I got the Pz38H735t to save up for a month of premium, and then stay on premium.
The best "money makers", provided you have the patience and talents to make them work, are the artillery pieces. My Hummel is a decent earner in even a bad match. But artillery doesn't usually make experience points real well, especially not experience.
I've found the Sherman, although it is short on armor and firepower, actually does well if you use it as a highly mobile sniper, and avoid slugging matches. I have a Sherman Easy 8 now, and I really like it. It really needs a 90MM tier VII gun option, but it does okay as it is.
My PzIV has to be the best tank I have for ease of play as well as credit and experience farming. I went back and bought my PzIV to earn experience for the Hummel, but it was so good I kept it.
The tank destroyers are a tough deal. They're really handicapped in the city battles, and a couple of other battles that lack cover, such as Karelia. I have a JagdPanther now, and it does fairly well, in the right battle. In the wrong battle, well, you can come close to losing credits on it.
Possibly the best all around medium may be the VK3601H. I do well in mine most of the time, although it is parked right now while I work on the U.S. tree.
While I really like my Tiger II, I'm not sure I'd tell anyone to get one. You really have to play it carefully, as a cautiously aggressive sniper. Honestly, the Russian IS series is far easier to play.
I think everything I own now has the top tier equipment available for it, and all but the Easy 8 Sherman, and maybe one other have 100% crews working on their 1st or 2nd secondary skill.
Honestly, playing WoT is not much different than AH II, with regards to the fact that situational awareness is your most vital skill.
Finding people to team up with in battle is a really good thing, as running with a good platoon will teach you a lot. However, not very many players have kept a lower tier tank, so you either can't run with them, or you get dragged into battles where you're at such a disadvantage that you're a burden to the team. I kept my little tank, but I'm in the middle of remodeling my house and getting ready for a trade show, so I haven't played much in two weeks.
Getting on the flamewarriors channel is a good idea, there are usually 10-20 guys on that channel on a given night, U.S. time.
