The back page of my set of rules has several systems to try to sort this out. Appendix 6 of the rules (from here) says:
3:1 Exchange
At any time, a player may discard any 3 cards from his hand and draw the face-down card at the top of either the Minor Improvements or the Occupations deck. This card is placed in the player’s hand.
10-3
Each player draws 10 Occupation and 10 Minor Improvement cards and discards 3 of each.
Mulligan
At the start of the game (and only at the start), a player may discard all 7 Occupations and/or Minor Improvements and draw 6 new cards of that type. (If the player is still unhappy, he can keep trying this, always drawing 1 card fewer than he discards).
Draft
Before the game starts, each player receives a hand of 7 Occupation cards as usual, then chooses one and passes the rest to her left-hand neighbor. Each player chooses one of the 6 new cards and passes on the remaining 5. This continues until each player has 7 cards. Repeat this process with the Minor Improvement cards. This variant allows players to create better combinations of cards than with a purely random distribution. We recommend that each player should have played Agricola at least 4-5 times before trying this variant.