Make sure to review your prenuptial agreement as early in the game as possible.
Photocopy all the financial documents you can find, particularly if actual incomeas opposed to reported incomeis going to be an issue.
Be discreet if you date.
Consider hiring a private investigator when appropriate in issues concerning child custody.
Always check with your attorney before signing any agreement or taking any major steps such as moving out, withdrawing money from joint accounts, stopping credit cards, hiring a private investigator, or trying to tape conversations.