Store-bought dressings are convenient but expensive and may not be of the best quality. Homemade dressings are better, with a three parts oil to one part acid ratio. Experiment with different oils and vinegars. Keep a few jars of homemade dressing in the fridge, like honey mustard vinaigrette and Thai-inspired peanut dressing. They last about a week and can be used to dress individual salads.