there is no such thing as karma, if you are helping others for karma its as morally inferior as doing so in expectation of reward from god(as opposed to doing because you feel good in helping others or care about other without seeking anything in return). However helping others for any reason is better than not helping at all.
Karma is Cause and effect which is a natural phenomena of this universe, A+B=(A+B)2
Newtons laws
in crude words you taunt me in real life, i will break your teeth there and then itself.That is cause and effect in work
Any help or harm will be considered as good or bad karma. which you have to eventually face it.Unless you become Brahmachari not celibate( the one who considers good and bad as equals and expects nothing,but realizes him/her to be the part of Brahman, then at that time Karma and this worldly restraints are off.)
a common man can begin by not wasting food and trying to see if surplus food can be given to needy.
in my personal experience, one can volunteer for help to several help group either by making some sort of material or money donation or offering help im form of kitchen service that cater to mid day meal scheme in schools.
Bro, we took in many homeless kids and tried to give them best education,care and family.They just ran away.because they street kids living on the street are street smart they know how to make money, even a 5 year old kid on street is clever even than your average teenage kids at home whom you sent to best schools.They speak with experience, not theory as schools teach kids.
They dont want to go through all those school things ,when they are getting free money on street.
Do you know the beggars on street have a certain hotels where they get credit for a month ,They eat Biryani or best food everyday.They earn around 500 to 1000 rs a day which some IT people dont even earn..But the pay depreciates as per age.so as they age, they become a syndicate and employ younger kids to beg for them and take their cut everyday.
I used to think they were hungry so went around giving them packaged meals or bread everyday,some of the beggars used to say "bread hai or meals ki pack hai" and frown because they had a biryani before.After i left the spot they would feed the food to dogs.Such is their choice of menu.
But Not all are the same, there are some genuine people who cannot beg out of honor or feel insulted to beg,instead they would starve etc. or real people who are starving, You need to understand them and gauge their response.Differentiate between the haves and have not's it takes some time if you ventured around giving free food,blankets and other things. etc.