Motor sport photography can be tricky. The cars or bikes move really fast and often there are people's heads in the way, but there are things you can do to improve your shots:
A camera with fast a fast AF function, such as those found in Samsung's NX Series, are ideal for action photography, plus the short shutter release lag featured on many of the NX Series cameras helps photographers capture fleeting moments before the subject has left the frame. As it's hard to get close to the track, a lens with longer reach will help you get the frame-filling shots you're looking for and don't forget your spare batteries!
When it comes to actually taking your shots, blur can be a massive annoyance, but it can also be used creatively to get the effect of speed and movement in a picture. How good you are at panning, what shutter speed you use, how fast your subject is moving and how much light's around will make this harder/easier every time you visit the track. Just remember: too higher shutter speed and you'll just freeze the shot, too slow and they'll be too much blur. Also, try and find a clutter-free backgrounds to stop distracting objects spoiling your shot.
As the car begins to work its way to the edge of your frame, turn your upper body, keeping your bottom half still, following the car's movement along the track, keeping the pan going even after the car has moved out of frame. to ensure the pan is smooth, keep your feet slightly apart, creating a sturdy base and if you're working hand-held, keep your arms close to your side. Lock your focus and use continuous focusing if your lens struggles to focus on the car and switching to burst mode will mean you'll be able to capture a series of shots, increasing your chances of capturing a cracking shot.
It can be annoying if there's a big crowd, and no matter how hard you try, people's heads are in the photo. Sometimes, they can help create the sense of a crowded scene, but when they block out part of the car or bike you are photographing it can be annoying. The only thing you can really do is be patient, and wait for a gap in the crowd so that you can move further forward. Be courteous – if you explain that you'd like to take a photo, most people will move and allow you to do so. If you are in the stands, try going backwards up them so that you are able to photograph without people in the shot. A bit closer to the track, position yourself on a bend to maximise your chances of capturing the cars in action.
Shine can be a big problem in motor sport photography. The sun glaring back at you off a car window or bonnet, for example, can ruin a photo. The solution is to simply change the angle of your shot slightly to minimize the glare or fit a polarising filter. Surprisingly, rain does not necessarily have to be your enemy in motor sport shooting. Just make sure you bring covers for your equipment so you're ready to shoot and consider packing a mac and brolly too. Spray coming off the track can look brilliant in a photo as cars and bikes go by. The same technique can be used in the dry for things like rallying too, the dust kick up from the cars will look amazing if you can capture it.