Do you look like you can play tennis? That might seem like an odd question and every once in awhile I am fooled but generally I can tell how good a player is with the first impression. There are certain things that good players have in common that let you know they are serious about the game. Here are just a few of the things that standout for me:

Matching racquets - It isn't a must to have extra racquets but good players know the value of making sure their backup racquet is almost the same as the racquet they normally play. If you are using a wooden racquet at this point I'm not liking your chances at the US Open.

Proper shoes - I had a friend once whose first round opponent came out in cowboy boots. I doubt if this will happen in your lifetime but it was a pretty sure bet my friend was going to win the match. Good players wear court shoes not running shoes.

Bag - Most good players have some sort of bag they take on the court. This can be a thermal bag for the racquets, a backpack, a small court bag, etc. Your bag is a good place to keep extra socks, t-shirts, sunscreen and other items you might need during your match. A player walking out bouncing his/her one racquet against their shoe has "beginner" written all of them.

Shirt/Short/Skirt/Dress - It isn't the most important thing to have the most expensive outfit on the court but looking good makes you feel good and feeling good helps you play good! I don't think I would look that great in the outfit Kournikova wore at the Australian Open but it did inspire me to make sure my shirt and shorts matched.

You may or may not agree with my ideas on how a good tennis player looks. Of course Lleyton Hewitt could use a wooden racquet with a press and no bag, wear running shoes, and probably wear Anna's outfit and still beat most opponents. However I would suggest trying that after you win your first grand slam event.