Protective films are terrible to apply but it is not a good idea to be without her. The cell phones they scratch a lot in your pocket or backpack. I found a very cheap solution in DealExtreme: This set of 5 protectors for only 2 dollars and little.
In the photo appear just 4 well one of them I applied and I threw away the cover!
Each of them comes with shield and this cleaning cloth.
There's no glue: simply remove the protection indicated by number “1” and apply. You can remove several times before leaving definitively. The good news is that there are five, If you don't have four more chances.
Worked great. Were some bubbles, but this is normal! I leave the link to the product on DealExtreme:
Set of five LCD protectors – http://www.dx.com/pt/p/protective-pet-matte-screen-protector-guard-film-for-samsung-galaxy-s3-i9300-5-piece pack-138749 #. U_FqjPldX08
Other accessories for Samsung Galaxy S3 – http://www.dx.com/pt/s/Samsung Galaxy i9300