Here are my top three in each category.

BEST

These are the only things I carry in my everyday camera bag.

1 - SLR. It doesn't matter which one. What matters is the larger sensor and the ability to shoot RAW.

The sensors in SLR cameras are much bigger than point and shoot cameras. Even if a given point and shoot has more megapixels than an SLR you will get better images from the SLR. For more on the benefit of larger sensors, c|net has a good explanation here. Buying an SLR doesn't mean you have to make shooting more complicated. When moving up from a point and shoot leave the SLR in one of the fully automatic modes. You can still use it like a point and shoot but you'll get better pictures thanks to the larger sensor. Start exploring the more advanced features when your comfortable.

RAW is a term used to describe a special format that SLRs can use to save images. RAW takes all the information captured by the sensor and writes it to a file with no processing. It is literally the raw data from the sensor. The RAW formats are manufacturer specific, so RAW files from a Nikon (saved as .NEF) camera are not the same as a Canon (saved as .CR2).

RAW has one important advantage over JPG - you can still change your mind about some things without degrading image quality. When an image gets converted to JPG in the camera all the settings like color temperature and color saturation levels are applied to the raw sensor data then saved to JPG. Using RAW, you can fiddle with many attributes of the photo with no loss in quality. This is an important learning tool. You can manipulate the pictures with image editing software to figure out how to fix what didn't work (with some limitations). Are the colors off? Maybe you set the white balance for daylight and the shot was under tungsten bulbs. Change the white balance and see if you're right. Is the shot too dark? By how much? Bump the exposure 1/3 stop, 1/2 stop and see what would have worked.

There is an ongoing religious debate in the photography community about RAW and JPG. My recommendation is always shoot at the highest quality format you can. You can always delete, crop or re-size later but you can never re-shoot. Why take the chance of capturing a great picture then wishing you had recorded it in a higher quality format?

2 - Extra battery and memory card. These are the two most likely parts of your kit to stop you in your tracks when shooting. With extras, just swap and keep shooting.

3 - Polarizing filter. This is the only filter you can't "fake" in software. It will cut out the glare from reflective surfaces like metal and water. It will also intensify color, contrast and help pop blue skies. It will also act as about a one stop neutral density filter which might come in handy when you want to cut down on the total amount of light coming into the camera. For example to open the aperture a stop or two when shooting a portrait on a sunny day. Check out the Wikipedia entry for more details.

WORST

1 - Printers. If you like tinkering with printers, different papers and effects go for it, otherwise outsource! Printers make me nuts, so that's what I do.

I tried several local printing spots and settled on Costco. Surprisingly, their prices are the lowest, they have a wide selection of print sizes, can do up to 11x14 the same day and the print quality is quite good. Their website has a pretty foolproof upload tool. I can place orders online in just a few minutes and pick up the same day.

For higher quality prints I'm just starting to experiment. mpix is first on the list. Other suggestions appreciated.

2 - Built in flash. You don't get much choice on this one. They are, well, built in. The problem with built in flash is the strength and positioning of the light. The light comes from straight in front of the subject and looks unnatural. In our day to day lives light generally comes from above then diffuses and reflects. That's where an external flash that mounts on the hot shoe of an SLR comes in handy.

Here are some tips to make the best of the built in flash. 1) Don't use it. If the lighting is good but just not bright enough, dial up the ISO a bit, but not so high that noise becomes a problem. Indoors try to move the subject to a window or turn on some lights. 2) Reduce the flash exposure compensation. How to do this varies by camera. I find that one full stop is about right indoors. 3) Put something in front of the flash bulb to diffuse the light. Even one ply of toilet paper held on with a rubber band will make a difference. I bought a Lumiquest Soft Screen and am quite satisfied. It folds up and slips into a camera bag easily.

The one thing built in flash is very good at is outdoor fill flash. I still dial down the flash exposure compensation, experimenting on a few shots to get it right.

3 - Mini tripods. Most SLRs are to heavy and will flop over anyway. The tripod has to stand up somewhere so why not just put the camera on that surface. If it isn't level you can always level out the shot in software later. There are small bean bag products out there you can use to seat the camera which seem like a better idea but I haven't tried one yet.