Most ham radio experts agree that the key to a good station is a good antenna. You can buy one at DX Engineering or Ham Radio Online, but it is fun to build your own. The techniques you learn can help with repair of ones you bought.
The types of antennas are usually wire dipoles, verticals, and Yagis.
The easiest way to get started is to build your own dipole. A standard dipole works great for a single band. End-fed dipoles are popular since they cover multiple bands.
An antenna kit is a great place to start building.
Here are some options:
Come to a RARS Parks on the Air event to see antennas and test your own.
RARS Field Day is a great opportunity to see different antennas that participants build and put up.