One approach that is helpful is to not take more of something that you need than you need. Example: If you are going out somehwhere sunny for a week, you are probably going to need/want sunblock. Instead of taking an entire bottle or tube, transfer some to a smaller vial or bottle. I do the same with olive oil, which I always take to cook with. For things like toothpaste and deoderant, travel sizes are the way to go.

Also remember that items of clothing can vary greatly in weight. If I think I will need long pants, I take a sythetic pair that converts to shorts by zipping off the legs. Not only does that eliminate the need for two items of clothing, the pants weight a lot less than, say a pair of jeans.

Just promise that you won't cut down the handle of your toothbrush.