One should pay attention to a few points while buying a screen guard for one's smartphone.
Go for a protector that meets your needs.
The protectors essentially come in three varieties.
1. Clear screen protectors - These are the most practical at what they do. They protect your screen from day to day beatings. Some of them are capable of removed and re - applied.
2. Matte finish protectors - They serve as anti glare protectors in addition to protection against cracks and damages. But they produce distortion and rainbow effect.
3. Privacy protectors - They can restrict viewing angles in addition to being the protectors in the usual sense of the word.
After choosing the one that suits you, pay attention to further points as follows -
Look for those protectors which have been laser cut and of precise dimensions suiting your phone. This becomes more important when your phone has a couple of sensors and front camera.
Do not go for protectors that come in packs - 2, 4 or so. They normally do not last longer.
Avoid those protectors which claim to be reusable. They do not have good adhesive properties and as such may peel off from edges.