If possible, wait to dress the salad until right before eating so that the ingredients stay crisp and don't get soggy.
The salad dressing, stored in a glass jar or Tupperware container, will stay fresh for 3 to 4 days.
See the "Variations" section in the blog post above for ingredient suggestions that will add even more flavor to the dressing.
A blender (I use a Nutribullet) will give the dressing a thinner, runnier consistency. It will also do a better job of chopping the herbs so the dressing will be smoother. A food processor will keep the consistency slightly thicker (more like a dip than a dressing). Also, it won't chop up the herbs as finely, so the dressing will have more texture.