I keep a few things at hand to make it easier to open my paints and mediums when I need them. I find a hot hunky studio assistant works the best, but even the best assistant needs to go home occasionally, so here are a few less sexy but equally as helpful tools I've found work for me.
1. The most obvious way to make sure your supply is easy to open next time is to wipe down the opening/mouth of the jar after each use. Hardware stores sell bags of cotton rags for just such an occasion (these also come in handy for other uses, which I will explore in a future art tip post). Of course you may not want to take the time to do this, I know I get so excited by the colors and the action of painting that pausing to wipe down my supplies is at the bottom of the list.
2. The next tool that can help in your quest for color is an old fashioned paint can opener. These are sold to open house paint, but the end can be slid between the lid and jar to loosen dried paint.
3. A great accessory for those with smaller hands or stiff fingers is a pair of grippy gloves. I find these a lot easier to handle than those grippy circular jar openers because they are on your whole hand instead of just in your palm. I use these for kitchen as well as studio, though not the same pair. I bought the ones in the photo above at Harbor Freight, at a ridiculously low price. (If you machine quilt, these are also helpful for holding the quilt sandwich as you work).
4. Pliers are great for paint tubes.
5. Another strategy, similar to the "just clean it off" method, is to rub a small amount of petroleum jelly on the screwtop part of the lid. This is good for tubes of paint, but I am not sure how the jelly would mix with a water based paint or medium. The excess would help keep your fingertips moist though (hey, as Alton Brown says, multi-taskers are a good thing).
6. One last method I've employed is to use a sheet of plastic wrap between the mouth of the jar and the lid. This worked really well, especially with the plastic wrap that had the dots on one side. I'm not sure if they make that style any more. Plus, keeping a roll of plastic wrap around is kind of hard with a cat in the studio. However, if you choose this method, plastic wrap is useful for other art applications, such as texturizing and putting over paint on the palette to help keep it damp between painting sessions. And you can wrap damp brushes in them and store in the refrigerator between uses (that one comes from Martha Stewart; she was referring to house painting brushes, but I bet it would work for art brushes too).
These are the strategies I've used to make it easier to get at the art supplies when I need them RIGHT NOW. If you have any methods that work for you, please share in the comments. Maybe I'll find a new favorite.