As mentioned above...
1. Put your wallet back in your pocket. Spend several months familiarizing yourself with what is available that interests you and what those prices are like. An informed buyer is a smart buyer. Some of those pieces may sell in the meantime, but at least you will be wiser and happier in the long run.
2. When you do decide to buy, buy what you love. Don't worry about what the market likes or you think will make your friends jealous, or because something seems like a bargain. Buy because it kicks you in the gut and you love it. Not like it, but LOVE it. Those are the pieces that will stick with you thick or thin. Other stuff comes and goes, but those real genuine gems, they are much harder to find and you don't want to be caught cash-short when they pop up.
3. At the end of the day only your opinion of the piece matters. It's your money and when its all paid for and the con is over, the internet is off, its just you and the piece at home. Who cares about what anyone else thinks of your collection as long as it makes you happy.
4. Don't go overboard. It's way too easy to spend too much and there is always something else around the corner.
5. Don't buy art as investment. You can think about value of the piece when weighing what to pay or deciding to buy, but don't think it will turn X profit or even retain its value. Buy it because you want to own it and the joy it will give you. The rest should just be gravy.
6. Re-read and believe #1. It's soooo important to get your legs under you before the wallet comes out. There is so much variance in pricing that you could get a deal or reamed very easily and knowing the difference can save a lot of money.