What do you need to careful about when you buy a digital camera?

I dont know if there is world wide standard... I live in australia...

You want at least 4 mega pixels and an OPTICAL zoom not just a digital zoom. I would also recommend getting a camera that uses standard batteries instead of a rechargeable camera. Its easier to just change out the batteries when your on the field. I also find that companies that specialize in photography like Canon do better than those that specialize in electronics like Sony. By the way don't get sucked into the memory stick trap by Sony, SD is far more universal.

i look for how many mega pixels it has and shutterspeed mainly.

well some things to look at are the pixles the higher the number the better the picture, and dont pick an off brand they usually dont work, and always make sure there is some type of warrenty

cnet.com has reviews and they don't sell any.
i have a canon,uses aa rechargeable li-ion batteries are aa size,so in a pinch i can throw in any akalines to keep shooting.model S1IS. us $ now about $280. 3.2 mp,which is sufficent for 8x10" prints;movie mode,and accepts a special telephoto & wide lenses (cost extra).even have a wireless remote for it (20).i read consumer reports also when shopping for it.best of luck.

well... you gotta be careful with the battery, better the camera have two changeable battery instead just one rechargeable li-ion battery... when u need it just change that with a new one set of battery, even this supposed to have at anytime on your pocket some "brand new " batteries... Other thing : take care 'bout the resolution, a "clean" one are better then interpolated. Remember : you buy a digi cam for pictures, not for Hollywood, so... don't need to have high capabilities to movie mode... ignore it... just take a good picture and... engoy it !! I'm here for more suggestions, folks... buzz-me anytime !! See ya'.

try to get one that goes faster- it gets boring waiting more than 3 seconds to take another picture

It greatly depends on which type of camera you want!
There are currently several ranges:
- entry level (cheap, basic functions)
- pocket cameras
- superzoom cameras
- bridge cameras
- DSLRs

I would look at the following things:

- zoom range 35mm equivalent. Many cameras have something like 35-xxx. This is great, but 35mm zooms may be easy to manufacture, but they are not wide enough for interior shots. To me, a 28-105mm equivalent is way more useful than a 35-114mm.

- image quality at 200 ISO or more. Current sensors fit 6 to 8 megapixels on a surface smaller than a nail. This has huge setbacks in terms of sensitivity to light. 99% of current digicams are useless in low light situation and provide very noisy images at 200 ISO and greater. There are exceptions though, with some Fuji Cameras fitted with Super CCD HR sensors. Most (if not all) other brands, use the same sensors made by Sony.

No current camera is satisfying on both of the above criteria. You should read the tests carefully and find out which brand has the best records on these points.

Pixel count is interesting, but is less relevant than before. Any camera with 5Mpix should enable you to make prints of 8x11 inches. A larger number of pixels may be interesting if you want larger prints, but the more pixels there are, the noisier the image is at high ISOs.

I look for pixels to be 4 or higher (the higher the more expensive but the better the photo quality especially for enlarging the print).
Also optical zoom is important. Digital zoom is just what you see when zooming in on subject. Optical zoom is what camera is capable of zooming in for actual picture. Many are 3x for moderately priced cameras. I am looking at the new Panasonic with a 6x optical zoom.
Also speed of actual picture taking speed (from when you push the button to when the camera clicks and takes picture). The slow ones can take long time and you can lose your subject's pose.
Also, the light fill qualities so that in low light areas you don't always have to use a flash which can cause red eye and others flash back errors.
That's about all I can think of right now as far as what I look for in a non professional camera.