[dansalmo]

Using the suites and ranks of the cards in your current and/or previous hands, including the order they are received is a good method. Using any thing else that others have access to such as board cards or time can deos not technically increase the randomness. There will be limitations on some hands such AA, but if you remember that you folded 2h7c last hand then you have a large variety of random numbers to choose from.