Seriously - salt is pretty essential for health, really. You get all sorts of valuable trace minerals in there.
Garlic powder is disgusting, never use it.
The request for what spices to use is a bit too vague for me, I'm afraid. I mean, I love thyme, rosemary, basil, oregano, cumin, cinnamon etc but it really depends on the dish. A spice rack with 30-40 spices is more-or-less essential for any kind of serious cookery. Actual live home-grown herbs are superior of course, if you can swing it.