Gift cards are a good idea ...
Yes, they can be. It is good to get to know a person. Drug addicts and smokers and alcoholics can sell gift cards and clothes and even certain kinds of food you give them. There are people in living quarters, too, who sell their food stamps so they can buy cigarettes.
The more you set up a way or a system for helping the homeless is the more certain ones can figure you out so they can use you and turn your ministry to their purpose.
So, if you have a system or program, one-size-fits-all ministry, it is likely ones will learn how to work it while they keep getting nowhere. But there can be honorable and appreciative people who will benefit from what you do. And ones will deeply appreciate having you to share with them as Christian family. But if you treat everyone in the same generic way . . . based on some preconceived theoretical and/or emotional way of seeing them > they could benefit from loving you and praying for you, while you are busy with your gestures!
So, I consider > find out what's really going on. And give out simple stuff so they aren't suffering so much on the street. But see how you can personally share with people to help them to Jesus so He is guiding each one personally. Anyone functional to get help can be referred to services . . . possibly, in your area. So, it might be wise not to try to rescue anybody. If someone is not functional to cooperate with being checked out and guided by professionals, it is likely they also will not do well with you.
So, I would say get to know what professionals are doing in your area, and share with mature members of your church, who already have helped homeless people.
I think it can work to get to know a person; but make sure you are around other people, in a program center where you volunteer, or a shelter, or bus station, or your church. I would not get alone or socially isolated with anyone you don't know. By socially isolated, I mean the person has more and more say and control about what you do. Make sure you are doing what you know God is guiding you to do; He does guide us to take risks, in order to love people, of course . . . but not what certain homeless people or others might say we have to do. It can be just like how a fake boyfriend might dictate > if you love me, if you trust me, you will do such and such.
You do not need to trust someone you do not know. God has proven Himself to us; this is why we trust God through Jesus. You can expect someone to prove himself or herself to you.
I have lived on the street, on purpose, in order to see what I could do for street homeless people while I as a Christian lived with them as their neighbor. Plus, now I share in a needy persons' outreach truck ministry in a city.
And I would say people ministering act according to what they think they see.
But if you do what God has you do . . . yes, evil people will use it in an evil way, while honorable people will greatly appreciate you caring about them. The honorable ones, I would say from experience, will mainly appreciate having you to love. And your good example of how to love while trusting God will do us the most good, with your prayer
God knows you care; He will make the way for all He is committed to doing with you. And my opinion is this will be first with you learning how to obey God in the ruling of His peace in our hearts > Colossians 3:15 < so you discover what He really has you doing for all people, not only with attention to homeless people; because God is all-loving. And grow as family with Jesus people who are maturing and helping you to walk with God and love any and all people. And as you grow in healthy life as a Christian, this can spread to help all people, not only the homeless. Always be ready to love and bless and help any person who is not a Christian, because everyone without Jesus is not at home with God.
While I was homeless, what helped me the most, for ministry, was people who simply were gentle and humble with me. They always knew what to do with me. We simply talked and sometimes they shared things with me or even took me to their homes. But most of all was their example of being humble and quiet and gentle and kind . . . how I could see I needed to become so I could share as family with God's people. What I myself really needed was to get into sharing as family with Jesus people.
So, most of all is how you and your church are healthy in love as God's family, so you can adopt newborn children and care for them with good example and sharing.
Each street homeless person is unique. So, if you are seeing them as a group, possibly you do not know what is really going on and how they really are. So, I would say trust God to guide you. And enjoy discovering what He is committed to doing with you.