Printed signatures have no increase in the value of a card, unless the signature is a limited print issue like this:
1994 Upper Deck Collector's Choice Gold Signature #340 - Ken Griffey Jr.
Courtesy of COMC.com
The normal version of the card might be 50 cents, but these versions have sold for $10 for this Griffey Jr card.
Autographed cards in packs come in two flavors: on card autograph and sticker autograph. There is a premium for having a signed card compared to a sticker. Sticker sheets are mailed to players and they can sign 10,000 in a row; then the manufacturer (Topps, UD, whatever) can apply the sticker to all upcoming cards of said player. Topps recently included sticker autos of both Tony Gwynn and Oscar Taveras after their deaths, since they still had them available.
Cards hand-signed were actually touched by that player, so they are worth more to collectors.