The best sales people are often the most sensitive. They can read the body language of their buyers. They know that some buyers prefer to be left alone to do their browsing, while there are others who need assistance right away. Salespeople who follow you wherever you go in the store can be annoying. But some people like that. If you need assistance, just ask. If they're too busy for you, get out. If they ask you and you want to be left alone, tell them "just looking" and they should be able to take the hint.