If you are in an alliance share all your extra goods with your alliance members or member. Also ask then to keep an eye on your might while you are gone. If it is going down you are being attacked they can come defend you.
Put your taxes down to the minimum. You want to be able to pay your knights and make no profit to almost no profit. This way you are not making gold that will be stolen.
Hide troops in the sanctuary. Make sure you have enough to feed them though because they will leave if you do not.