How to try out infrared photography?

(I have a Nikon D5000 and three different lens)

With most DSLR's, you'd need to pay to convert it into infrared…

Conversion is only necessary if you want 'normal' shutter speeds, just to try it out all you need is an IR filter to fit your lenses filter thread size.

Be warned in an unconverted camera shutter times will be long (10 seconds - 1 minute plus) even on a bright hot day, so a tripod and static subjects are necessary. Interestingly the shutter speed does not increase that much even when it's dark and your outdoors. Film cameras are more sensitive to IR and shutter times will not be as long.

Converting a camera makes it useless for 'normal' visible light photography.

It's easier by far to turn a normal colour image into a pseudo IR in post processing, it really will look the same.

You can buy a nice Nikon 35 mm SLR with lens for under $100 and use it with your existing lenses and IR film to "try out" infrared photography. You will also need a deep red filter (25a) to capture IR on the film.

Once you convert a camera like the D5000 to IR (about $350), all it will shoot is IR