How should rosemary be watered. I either over water or under water.

http://homeguides.sfgate.com/signs-overwatering-rosemary-bush-97162.html

I bring mine in out of the herb garden each year. I put it on my kitchen sil over the sink, water when dry soil and in between I give it a mist of water.

All depends where you live. Is it in ground or in pots? If in pots, just stick your finger in 2" down, if dry it needs water. If damp, check again in a few days. If in ground do the same thing until you get the hang of it. Rosemary does not like wet feet and does best in well draining soil. Where I live it grows like a weed year round, in other climates it can be considered an annual.

My Rosemary is about two years old, in a big pot, I water it when there hasn't been rain for a week if it is not too hot out, otherwise more frequently. I water it about once a week when it is overwintered in the house. Go by your judgement or get a moisture meter to stick in the soil to make sure it is not too moist. Mine goes in a south window, but doesn't get direct sunlight and does fine, it didn't get leggy. It was really the only herb that survived well enough to go back outside without replacing.