:: Pack whatever you plan to take then put half of it back. (Most people tend to take far more clothing than is really necessary)

:: Pack with confidence.

:: Pack clothes which are complimentary with each other and can be used in combination to make different outfits.

:: When traveling with a companion. Pack one of your outfits in your companion's suitcase and have him/her do likewise. Doing this will be invaluable should one person's bag be delayed upon arrival at your destination. (If both are lost, oh well, at least you tried your best)

:: Bring a raincoat. A travel raincoat takes up very little space and can be a lifesaver...should it rain of course.

:: Try to pack clothes with fabrics that require little care (wrinkle-free) (cotton-knit etc..)

:: Pack a change of clothes in a carry-on piece of luggage in the event that you make it to your destination but your checked luggage ends up somewhere far away.

:: Try to visualize what clothes you will need on a particular trip (with regard to climate, events you will attend etc...)

:: Toiletries-don't bring full sized bottles, bring mini-bottles or sample sizes to conserve space.

:: Wrap toiletries(etc.) in plastic in the event that items may break or leak and use plastic containers.