If you’re going to be doing sports photography, a fast shutter and a powerful zoom are the first musts!
Tim from boudoir photographer manchester reckons that extra batteries and memory cards in your backpack will prove very useful when games get longer than anticipated.
For a Tennis or Car Racing event your camera need to shoot at iso 200 with at least f5.6 frames per second. You have to shoot a minimum of 400 photos in order to have reliable material when you edit.
Choose a location when you can use a telephoto and a monopod with certain comfort.
If you want images free here are some sites:
Image base, you need to attribute the photos when you use them.
Morgue File, absolutely free to use
Stock.xchng, a free account is needed to download photos and every one of them is owned by photographers who set the terms for the use. In general terms they do not allow them to be sold to a third party.
Flickr, you can use the photos and have to attribute them. Cannot be used for commercial purposes.