I found the only thing that worked was a shotgun approach and I do not mean shooting the fleas with a shotgun. 
I mean: you have to keep the place really, really clean. All pet bedding must be washed in super hot water (and Borax – I add it to the washer) and then treated with Frontline spray or Borax powder. I double down and sprinkle clean bedding, carpets, upholstered furniture and the like with Borax. With carpets and rugs, sprinkle Borax all over, walk around to scruff it in, and then vacuum up the excess. Don’t forget to pull up the couch cushions and vacuum any rugs or carpets under furniture. You seriously have to move every stick of furniture in the house to vacuum every single corner, nook, and crevice. Bonus is: now you’ll have a nice batch of Borax in the vacuum cleaner so when anything you vacuumed up will die from the Borax.
I make a water-Borax solution and wipe down everything, mop tile and hardwood floors with it (this is also great for cockroaches btw), wipe down baseboards, pet crates, etc.
And then, think about the life cycle of of the flea. One flea lays around 20 eggs at a pop, which hatch in 2 days to 2 weeks. So, once you do all this, remember: YOU WILL HAVE TO DO IT ALL OVER AGAIN in two weeks. You will miss some eggs. If you can see 2-3 fleas, there are thousands you can’t see. They are all laying eggs in every nook, cranny, warm spot, and on every critter in the house and general vicinity. You can’t just treat 'em once and forget about it. That’s why a lot of pet owners put those drops on every 3-4 weeks – to nip that life cycle in the bud and prevent it from rebooting.
Now, I live in an area that is warm to hot year-round, so the vigilance against fleas here cannot be relaxed in the winter. I still treat the dog every month, even though I haven’t seen any. If the pet goes outside, they pick up fleas from grass and from dead critters and from live ones nearby. For all you know, your neighbors have a terrible infestation that has bled over to your cat. One sniff of another cat and BAM, the cycle starts again.
This Wiki article has a list of ways to combat fleas at the bottom.