Don't expect anything in return when you help, just cultivate the habit of being useful and God would definitely reward you, you don't know the way God would reward you through but no one dare God and didn't see the hand of God
Although I am not brought up to learn how to give, but I adopt the habit of giving when I see how happy I used to be whenever I recieve, so making someone happy as well should not be a problem for me. To me, helping is like making business, you pay a little and recieve much later
These days I have been receiving favour from someone I don't even know he can even be so useful like he is these days, this is the time I need help and I am receiving it. I gave him once and now he is giving me. If I didn't give him that time, definitely I won't recieve from him now. It is just good to be good always
Help, those you help may not be in condition to pay back your kindness and they would definitely never forget you if they are not an animal and someday you would receive back what you did either from those you help or from an unknown source.
Just learn to give