Thierry Tomasin describes the qualities of a great sommelier

What makes the difference between an average sommelier and a good one? Former sommelier turned restaurant owner Thierry Tomasin shares the fruit of his experience.

It's nice to be able to go to school and learn all about grape varieties, how to make wine and all the rest of the theory behind being a sommelier, but at the end of the day there's no substitute for practical experience. You have to go to the vineyards and work in a restaurant if you want to learn how to do the job properly.

Nor is being a sommelier just about creating a wine list. At the end of the day, anyone can make a good wine list if they've got money to spend. Of course it's important to have a variety of different grapes and styles of wine on your list, and it should reflect both the cooking and style of the restaurant.

But the real skill lies in understanding the customer and finding out what he or she wants to drink rather than imposing your own views on them. Even if the customer asks for something that seems like an inappropriate match - say asking for a Sauternes with a steak when you know they'd be better off with a good red wine - you can't dictate your own taste. You are there to guide your customers if they ask for advice, but you have to be flexible. You are there to give your customers a good time and leave them with good memories of your restaurant and you are not going to do that if you dictate your own tastes to them - doing so will make you appear arrogant. If a customer feels intimidated, they won't ask for your advice and they won't come back. Remember, after all, that it's the customer who is paying the bill and, ultimately, it's the customer who is responsible for the success of your restaurant.

Being a sommelier is not just about suggesting wines from the list. You should also pour the wine, polish the glasses and, if necessary, bring the bread to the table. Some young sommeliers seem to want to do the wine list and open the bottle, and then leave the dirty jobs to the commis - but this isn't right. Service is all about team effort and you have to learn to multitask. There are limits, of course. If the waiter pours the wine all night while the sommelier is serving the food, there's a problem in the restaurant, but within limits you should be a good team player. Furthermore, in these days of economic uncertainty, a lot of establishments have got wise to the fact that they can employ someone who's prepared to do it all rather than having a highly paid sommelier who refuses to roll up his or her shirtsleeves and help out.

Another part of the job is to train the staff in your restaurant to taste wine. Sharing the knowledge you've acquired is important. It's nice to talk about the wines, how they're made and how they're developing - but it's also an integral part of building the team and, as I've said before, a restaurant is nothing if it isn't a team effort.

Finally, you have to open yourself up to new experiences and the possibility of learning something. Indeed, there's always something new to learn in the restaurant industry. That's why it's so exciting - no two days are ever the same. If service was totally predictable, someone would invent a robot to replace sommeliers. Instead, think of your job as being like that of a conductor, and telling musicians how to play is like co-ordinating the service. That's what service means to me.

• Sommeliers