A revocable living trust is useless if it doesn't contain assets. Whether your purpose in creating a trust is to manage your affairs if you're incapacitated or to bypass probate at your death, it won't work if you don't transfer at least some of your assets into the trust's name. Which assets should go into the trust depends in part on your goals and your financial situation.
If you want to transfer assets to your heirs, all your substantial assets — bank accounts, real estate, investment accounts — should be placed in the trust's name. If you own land in several states, placing all that property in the trust will save you from going through probate in each state. If you want the trust to manage your affairs if you're incapacitated, then you should select assets that require someone to oversee them. Giving a trust ownership of your valuable antiques may make sense if the issue is probate, but probably not if your concern is incapacity.
If you share joint ownership of property with someone else, you may not need a trust to protect those assets from probate. Joint ownership with right of survivorship automatically transfers your share of the title to your co-owners. If you and your spouse own property together and plan to leave it to each other, many states speed up or dispense with probate. In some cases, you may be able to place your share of ownership in the trust, but you cannot divide community property that way.
If you have assets with named beneficiaries, such as a 401k plan or life insurance, those will pass to the beneficiaries without going through probate. There's no need to put them in the trust. The same is true of any type of account you've set up to include a pay-on-death or transfer-on-death provision. In the case of retirement accounts, you may actually hurt yourself financially putting them in a trust, as the IRS can treat this as a taxable withdrawal from your 401k or IRA.
You can use an Assignment of Property form to transfer valuable property without a title — jewelry or art, for instance — or even household and personal items to your trust. Check your state's probate procedure first: If your estate is small and your finances simple, the probate procedure may be easy and affordable. In some states, transferring a few major assets, such as out-of-state real estate, may leave you with a small enough estate that probate will be swift and uncomplicated.