"If I file for divorce, how can I protect certain assets (family heirlooms, etc.) from my ex?"
If the bulk of the marital assets are maintained in an account standing solely in your spouse's name, and you fear that he may ignore the court order and attempt to liquidate that account anyway, you may want to consider faxing a copy of the TRO to the financial institution in question. You should be aware, however, that this may result in the financial institution putting a complete freeze on the account; in some cases, the financial institution may not lift the freeze absent a court order. Since this could prevent your spouse from accessing these funds for legitimate expenditures, it is something that should generally be done only in cases where there is a clear and present danger that the assets will disappear.
If you are concerned about your spouse damaging, destroying, or hiding personal property, then a few basic steps can be taken. You can take those items most precious to you with you, if you move from the house. Photographs can be taken of all the belongings in the house to establish that they existed as of a certain date. Additionally, you may wish to investigate renting space at a storage facility, where larger items that you fear may be damaged can be kept until final resolution.