First of all, you should have a sound knowledge about historical arts and also the history of different museums all over the world. It will help you to give valuable information to other tourists that come to visit museum.
While working in the museum, you need to have a sound grip over your subject matter. You need to revise all necessary details about the important things of the museum and make sure you have researched all those things from different sources.
Try to find new facts of historical things that are displayed in the museum which will help you to enrich people with more information that they did not know before.
You should stay well hydrated by drinking water with regular intervals because guides usually have to talk too much and a lot of talking makes the throat dry. It will also keep your voice fresh and you will be able to keep the attention of the tourists intact.
You need to be enthusiastic while meeting to different groups of tourists and try to make a good interaction with them which will help you in making a strong impact on them.
Adding the element of humour while giving information about different things in the museum also creates a powerful impact and the tourists enjoy it.
You should also judge the expectations of your guests or tourists. Some people want detailed information while some other people want basic facts. So, you need to make them satisfied by delivering them as much information as required.
If you think that the tour will take hours, then pace up things and try to keep your guests fresh by adding humour. A long tour will make them feel bored, so try to make it fast.
Always keep asking your guests if they have any questions and if they do, respond to them accordingly. Make sure you have prepared well for responding all possible questions of the visitors.