How to taste wine in a restaurant and make it look like you might know what you are doing without appearing pretentious:

1. Briefly review the wine list, but don't make a show of it. Ask your date/partner/guests if there is anything they would prefer. Consider casually polling your guests for what they they feel like eating in order to set you up for success in the next step.

2. Feel perfectly comfortable in asking the waiter, especially if he is a designated sommelier (wine steward), for a recommendation. It is not a sign of ignorance, but rather an acknowledgement that the sommelier is more knowledgeable about the specific wines they serve and how they stand up to the entrees.

3. When the wine is brought to the table, the staff will usually present you the label, take a quick glance to make sure it is the one your ordered. Don't make a show of this. A nod or light comment "that's the one" will be fine.

4. The waiter will pour a small sample for you. Unless you actually do know what you are doing, don't turn this next step into a production. While a knowledgeable wine person during an actual tasting might go through an aggressive swirling, deep sniffing, and mildly extravagent, probably off-putting, sipping slurping process, you should not. Unless you are doing it for comedic effect. The reality is, as several others have pointed out, this step is really just to make sure that the wine has not "turned" or been contaminated by TCA (cork taint). You should, rather, swirl lightly and briefly, take a brief sniff, and short taste, look across at your date and give a light smile: not a knowing smirk, but rather a small grin that says "I am having a good time and this wine adds to it."

5. Set the glass down, tell the waiter something brief and polite like "Its great, thanks". Avoid making junk up. "Pefect for my lamb, the finish is quite powerful, I think it will do nicely" would be really really foolish.

6. Casually (casually!) indicate that he should pour for you date/guests first. He knows this already, but a slight hand gesture towards your date/guests indicates you do as well, without making a show of it.