Your goal is to get the highest payout hand possible. Therefore it makes no sense to try to bluff the machine by keeping unwanted cards or discarding favorable cards. You should always keep only the cards that have the best chance of yielding the largest payout. Pick out the machine that you are going to play. All video poker machines are not equal.
Different machines offer different returns so it's a good idea to pick a favorable one.
Also, it is a good idea to learn how to play one machine before learning another one since the playing strategies are different between the machines also. There is a video poker program that can do this for you. Always bet the maximum amount when favorable. All the progressive payout machines and even many of the others offer more favorable payouts when the maximum bet is placed. On these machines, your expected winnings will increase when you place the maximum bet.