Be friendly and sincere and if it's not too rushed they're usually happy to help no matter what you buy
The best information that I ever got at a shop was when I bought a dollar map and asked "where should I go ?".
As it wasn't busy at the time, the fellow at the counter had no problem coloring in different spots.
At another general tackle shop, I don't remember buying anything. They didn't have what we were looking for.
Still we hung out and chatted for a while until the guy looks at the clock and says.... "you know, if you hurry......."