You might make four heart tricks if it is your lucky day, but that is a long shot, and besides, it would be wrong to tackle hearts first. Why? Because if East has the ♥K and returns a spade, you would need to play on clubs where two tricks are assured. If East wins the first club, and returns his last spade, then you will be defeated if West has the remaining club honour and two more spades. In all, you would have lost two spades, one heart and two clubs. Now, try tackling clubs first and see the difference. The point is that if the heart finesse loses later on in the play, then East will have been exhausted of spades.