Easy, buy whatever new loot from Xur if you don't have it already. If you still have coins to spare buy "3 of Coins". Hop onto the Heroic playlist and pop a coin as you begin the strike. Now farm the strikes, after each strike just use a coin if the boss didn't drop an exotic or if the buff is gone (check character screen). I usually do like 10-15 strikes so I'll get at least 2 exotics that way, hopefully more. Also, let's not forget the legendaries you'll get throughout strikes.