Admittedly one of the reasons I haven't been touring wineries is because I know NOTHING about wine. I don't know how to hold the glass or swirl or any other of the wine etiquette everyone else seems to. So here's a cheat sheet to help:
You don’t always have to spit. If you’re trying many wines, you may want to spit. If it’s your favorite, don’t. Be selective about the wines you want to experience but not drink.
Do not wear perfume or cologne. Let the wine fill the room with aromas.
Swirl with confidence. Enjoying wine is all about two things: the aromas and the flavors. If you can't swirl wine properly, you're missing out on experiencing the lifted aromas that tease what's to come on the palate. It just takes a little practice.
Act like you’re interested, even if you’re not. You may have gone along just to hang with your friend or just to drink. That’s ok. Just pretend you’re interested in the experience.
Learn a little about wine grapes so that you have some knowledge of what wine is made of. That way, when you're told the red wine in your glass is made of Cabernet Sauvignon and Merlot grapes, you can nod with confidence because you've read about those grapes.
Don't hog the bar if it's crowded. It’s just good manners.
Dress appropriately. Heels will sink into the ground if you tour the vineyard. Flats might be a better choice. Don’t underdress either. The best thing is “wine country chic” which includes layering. Even if it’s hot, the temp in the wine cave is usually 56°.
If you’re going to different wineries, leave yourself enough time in between tastings.