if you think that you cant do anything for anyone even if you want to you still can. if you think that you are not in a position to help a person, the one thing you can do and you are always in a position to do is pray for that person, you dont need money for that, you dont need a time or place for that. you can just be walking down the road and remember someone....just do dua for them..........for dua can do what no one else can do. if someone tells you to do dua and you are afraid that you might forget it, then whatever you are doing at the moment you should just take a second and leave everything and just turn towards allah and make dua for them.......what better thing can you do for anyone.