How do you apply your foundation? I generally use my fingers - which some makeup artists swear by, and others insist that it transfers germs. I'm not so keen on cosmetic sponges, though I've used them in the past. One of the main problems with beauty advice is that it's so conflicting! I think a judicious dose of common sense is generally what's required and also your own experience in knowing what works for you.
That said, I'm not remotely closed to trying new things in the quest for perfection (at the rate I am going, perfection will be achieved in the year 2525) so I bought a foundation brush recently. I got a relatively cheap one to begin with (an€11.99 Manicare job from my local chemist) because I reckoned that if I did like the results, I could always splash out on a more expensive one afterwards. Possibly false logic but who cares?
Foundation brushes are generally made from synthetic materials, for a good reason - synthetic bristles have a smoother surface so they don't absorb as much foundation, giving you really good even coverage. That helps to make your make-up go further too.
To use it, I dispensed some foundation onto the back of my hand, and then dabbed the brush into it. I applied the makeup using outward strokes from the centre of my face. It took a little bit of getting used to but the results were great - I'm definitely a convert. Initially my face was full of attractive looking brush strokes but as I got more adept, I got better and better at blending - and blending past my chin was a cinch as well.
The one downside to this method of application is that you really do need to clean the brush properly after each use - which is a bit of a pain, especially if you're in a hurry. But it doesn't take too long - suds it up with shampoo (what's good enough for your hair will be good enough for the brush) and rinse it out well under running water.