Get yourself a wide-mouthed ceramic or wooden container like this one.

Add some good vinegar, the kind that's still alive. Most store bought vinegar will have been pasteurized, which makes it pretty useless in this situation. I recommend using Bragg's Apple Cider Vinegar, as it's generally the most commonly available unpasteurized vinegar. 25% vinegar to 75% wine is plenty to get you started, and you can get away with less vinegar.

Put a lid on your container. It should not be airtight. My container has a loose fitting lid that works great. It keeps the bugs out, but the vinegar can still breathe. You can use some thick cloth if your container doesn't have a proper lid.