If you're anything like myself, you're prone to food-related accidents...but pretty much only when you're wearing something nice. This ugly beast reared it's head at me again when I took my wife out to dinner at the local French restaurant, West of Paris, for our six-month wedding anniversary. The restaurant was fantastic, but I'll be talking more about it some other time.
During the third course of the meal (a salad and brie course), I accidentally dropped a bit of the salad dressing, a vinaigrette, against my bright white shirt. Oops. Now, I didn't have anything with which to clean the shirt at that time, so I did the first thing you should always do when you drop something on your clothes. I took my napkin and proceeded to lightly blot (not rub) the stain. Yes, I still had a purple spot on my chest, but it was more important that I not have a stain tomorrow than the rest of the evening.
When we got home, I decided that the stain was primarily an oil-based stain, so I used a bit of liquid soap (I used our un-dyed dish soap, but our hand soap would have worked too), and just rubbed the stain really gently. For a bit of added moisture, a light spray of Club Soda, which we keep for cleaning only, and a few minutes rest should lift the stain the rest of the way. After doing a final rinse with hot water, I allowed the shirt to dry, and inspected it, and sure enough, the stain was gone.
However, before you can do much with any stain, you need to think about what's in it. There are three primary types of stains: Oil, Protein, and Tannin.
Oil stains should lift out with a bit of soap, gentle rubbing, and hot water. If it's not going so well, club soda and a rest should help. Protein stains on the other hand (blood, eggs, etc) should never be cleaned with hot water, because the heat in the water could literally cook the stain into the fabric. Luckily, all proteins are water soluble, and a soak in cold water with some gentle rubbing should lift most protein stains. If you're having trouble, hydrogen peroxide should help the process along (particularly with blood), just apply the peroxide directly to the stain.
Tannins are a tiny bit trickier. Tannins are most often found in two sources: red wine, and unripe fruit, so this type of stain is a bit less common than the other two. However, cleaning it requires a slightly different approach, as soaps (which tend to be based on fats and proteins), can actually set the stain into the fabric. If you suspect your stain to be at all tannic, don't treat it with soap.
Treating is handled primarily as a soak. Add 1 teaspoon of washing soda (Sodium Carbonate) to each half gallon of water you need to soak the fabric. Washing Soda is chemically very similar to baking soda, so it's very safe to use. The only note I'd leave regarding it is to try to make sure it stay's out of your eyes, and if it does contact your eyes, flush them with water. It's unlikely to happen, but while I don't think we should worry about unlikely events, we should be prepared to respond to them.
After about 30 minutes of soaking, the stain should lift out of the fabric, with perhaps some gentle rubbing.
In all these preparations, once the stain is out, you just need to wash the clothing, though it would be worth doing a cold-water wash for the first wash after a protein-based stain (just to be sure). Stains happen, and proper, gentle, treatment of the stain is key to keeping the garment in good shape for a long time. I can't speak to commercial products like the Janie Stick, either to their effectiveness or 'all-natural' claims, but in my opinion, the fact is the best stain-treatment products available are cheap, easy, and likely already in your house.