There are several different products on the market, but good old fashioned neatsfoot oil is probably best. Put it on, let it soak in for several days wraped up with a ball in the pocket of the glove (to preserve the shape of the glove). It may take several applications, but it will work like a charm.

Saddle soap and glove oil.

to make an old baseball glove softer buy a product called hot glove (usually u can get it at walmart) and follow the directions on the bottle after u do that u should put a baseball/softball (witch ever one it will b used for) into the web of the glove after that u need to wrap a string around it and tie it up u should leave it tied up for two to three days

I would go with glove oil, for sure.

If you don't feel like going out to the store to buy oil, it's a little known trick that regular shaving cream will do the job just as well. Just a little bit, don't be filling it up, and rub it into the glove...and you should never put a ball in the glove and wrap it, especially in the web. Reasons: 1. You should never catch a ball in the web, it is only there as a "last resort", and 2. You want the glove to mould to your hand, not the ball.