Draft Occupations/Minor Improvements
The Family version of Agricola is a game of very low randomness. If one player is consistently beating another, then the second player will just have to step up their game, there isn't really any satisfactory way around that! Maybe I am a purist.
However! The full game, with the occupation and minor improvement cards, allows for games where one player is significantly advantaged over another: some cards, occupations especially, are just better than other cards.
So here's what I'd recommend, to give you a headstart on your opponent: deal two piles of 7 occupations, and then you pick the best one from BOTH piles. Your opponent picks one from each pile, then back to you, until you have seven each. Do the same for minor improvements. (If your opponent really is thrashing you, maybe even pick two at a time instead!)
When you have great cards and your opponent has mediocre ones, it will be much more of an uphill struggle for him to beat you. And now you are playing a game of Agricola that could have been created by the luck of the draw - you don't have to make a new game that's Agricola in name only, and the purists remain mostly unirked :D