Sorry for the delay in replying - I just didn't get around to it.
To be honest I may not be the best person for handing out tips but I'll do my best.
Rather than repeating what the others have said I will add my own, please try to view my tips as additions and not replacements for what the others have said and also remember these are my opinions and are based on my experiences only.
1. Use RAW - I tend to shoot RAW+ jpeg using the PEF format. One of the largest differences I have found is that when using flash whilst indoors the amount of recoverable information that has been lost in the jpeg is shocking - give it a go.
2. Raw software - I use Adobe Camera Raw - I just can't get to like the Pentax version.
3. Store the camera in an postion other than lcd down, when I adapted a rucksack (until I can decide on which specialised photo back pack to buy) I stored it lcd down and this caused me some dust issues and kept finding that the dust on the sensor needed a wet clean - now I store it lens down using my cleaning kit jammed under the hand grip to take the weight off the lense mount - no more dust issues - I assume that it just falls off
4. Use the floating ISO option and restrict the iso between 100 and 400 - I usually leave it on this setting unless I have a sepcific use for the higher settings or wish to restrict it to the lower ones.
5. I changed the EV steps from 1/2 to 1/3 (menu/ custom setting/ ev steps) - have a play with this as it affects shutter speeds (I like the 25 seconds option which you don't get with 1/2 steps) and the ISO's and probably other things I have not noticed or forgotten that I have noticed - have a play and decide which suits you best.
6. (yes I know you asked for 5) - I set the camera to the following as it suits my needs the most, wb when using flash to setting 2, digital preview to include bright/dark areas, metering mode as multi segment, drive to continuousand af area as selectable - also of course update to firmware version 1.30 if you have not done so already - I change the settings only when I need to such as when using the tripod I use the remote setting on 3 seconds delay to make use of the mirror lock up.
7. It's probably time for me to stop waffling.
Hope the above help