Use saddle soap to clean your glove. Put some saddle soap on a clean, dry rag. Rub the soap into the leather in small circular motions. Don't miss an inch -- clean between the fingers. You are working the dirt and grime out of the leather and bringing it to the surface. As you do this the soap will work into a lather.
Use a second clean, dry rag to remove the lather, which now contains the dirt and impurities that contaminate and harm leather, from the baseball glove.
Repeat Steps 1 and 2, if necessary. Making certain you have removed as much dirt as possible will help to add years of life to your baseball glove.
Let your glove sit for a day or two before following up cleaning your glove with conditioning it. This time allows the leather to breathe a bit.
During this time, you may want to begin folding, squeezing, bending and otherwise working your glove to loosen it up. The saddle soap is mainly a cleaner but also serves to condition the leather somewhat. You will already notice a big difference from before you cleaned your glove in just how soft and pliable it has become.
Use neatsfoot, mink oil or any other glove conditioning product to condition your glove, but stay away from petroleum-based products like Vaseline. Whichever conditioner you choose, work it into the leather well with a clean rag or small sponge. Dab (don't rub) the excess off with another clean, dry rag.
Let the glove sit for a day or two to absorb the conditioner. Reapply the condition, if necessary. Older gloves generally take more work to condition than new ones. Bend the glove during this time. Open and close it repeatedly. Punch the pocket with your fist or a ball. Work the leather to really soften it up.
Try out your newly conditioned glove with a game of catch.