A general rule of thumb for valuing most antique collections is the 80/20 rule, which is pulled from the Pareto principle of business. This means that 80% of the value will be amassed in only 20% of your items. Not all items in your collection will carry significant value, so it is important to put the greatest amount of effort into this 20% of your collection. Make sure to do extensive research into these items, and talk to an antique dealer or buyer for assistance in determining their worth.