Leather needs to be nourished... it will dry up and crack without care. Again, depending on the climate you live in (big difference between CA and AZ), you need to use some kind of leather conditioner/lotion once or twice a year. I'd advise against using anything in the first year (maybe two years), however. If you use your new purse heavily (daily), I personally like the first year to be the natural "breaking-in" period. I have no good explanation to this, so it's just how I feel. We don't use a hand cream on a baby's hand (who doesn't do dishes!) unless there's an absolutely positively good reason to do so. I believe it (baby skin or Vuitton leather) needs to be exposed to the air (and all the junk in the air), moisture, and oil & dirt from hands and other "stuff" in the environment in order to age naturally.
As far as what to use, I recommend "Leather Care" conditioner by Apple Polishes, although it does stain (makes it darker) young leather somewhat. It can be obtained at Burlington Coat if you have their store in town. Check their web site to find out where to get one. http://www.applepolishes.com/applepolishes/dealers/default.asp
What's NO NO is mink oil cream and alcohol... It contains animal fat that clogs the pores of the leather that need to breathe. It is seriously greasy, so it stains the leather big time. If you have Japanese catalogs & magazines (Perfect such & such) and happen to read the "care" section, many recommend mink oil cream to be applied thinly. WRONG! Believe me, you do NOT want to use mink oil cream.*
Mink oil spray on the other hand, does not stain the leather and it is a fine mist, so that it can be sprayed a little bit on the leather. I don't think this much (or little) mink oil should harm the leather at all. But for thorough conditioning, I recommend a lotion type, without animal fat. Don't forget to condition the strap!