Do not buzz in people into the store without making sure there is someone to help them. Do not just buzz someone in and let them wander around. If you see there is no help for them, buzz them in, greet them and immediately get someone or help them yourself. Don’t make them wait without greeting or without being helped.
Even though you have called someone to help them, they are still your responsibility until someone else takes them over. This can get tricky when several people come in at once but must be done.