The heelflip is the kickflips unloved brother. It's a bit trickier but it looks great and is fairly easy with practice. Start off learning this one fakie just like you should with the kickflip. Now you need to put your front foot just behind the front bolts and you might find it helps to have the very end of your foot poking off the far edge.
Put your foot in the ollie position but I reccomend just using your toes. You need to pop really hard, and using your toes makes the pop sharper and faster. Bend your knees and jump/pop at the same time. Now you need to push your front foot towards the front and far side of your board, scraping your heel along the grip tape and then flipping the deck
round but kicking your heel over the end. The board will only spin slowly at first, so either learn to spin faster or make sure you get plenty of air so there is plenty of chance for it to spin right round. Land over the trucks by bringing your front foot back in carefully but quickly. Bend your knees on landing and ride away.