What should be the intention and practices for Sadaqah?

I have 2 questions about the intention one should make when giving sadaqah, and hope someone here knows the answer. 1. Is there a recommended intention one should make when giving sadaqah? 2. Is it standard islamic practice (or is this cultural) to give sadaqah on behalf of another person to add barakah and/or make their life easier and/or remove some calamity from their life? i.e. Can I give sadaqah on behalf of a troubled family member? In the hope that this troubled family member will receive the blessings of me giving the sadaqah on his/her behalf?