If you are looking for ways to serve and invest in others look into local opportunities to serve in your community and sow into the lives of others you do daily life with and also international Christian organizations are a great place to plug in and show compassion to those who are considered the least of these.
I absolutely LOVE World Visions. I sometimes joke that if adopting a kid was as easy as they make sponsoring kids, I'd have adopted several on my parent's behalf. Two years ago in December I was at a Big Daddy Weave Christmas concert and they had a table filled with little faces of kiddos needing sponsors. Just starting my first full time job, I told myself I couldn't afford it and I was just going to look. Needless to say, the sweetest little face beckoned me and I ended up with a little boy in Tanzania. Then, last November I was browsing through other kiddos on their website, with no intention of sponsoring anymore and a year later I also have two girls, one in India and another in Sri Lanka. I don't tell you this to say, "Look at me!" but to say, if I can do it...so can you. I get photos, pictures they color for me, and letters...sometimes from the momma's. They also have all sorts of other opportunities to help families across the world, including the U.S....which is awesome!
I am also a huge fan of Samaritan's Purse and their Operation Christmas Child. I've recently heard a story of a little boy who got his shoe box, got one toy out of it, and handed it back because he thought he got to just pick one thing. He was thrilled with his one toy, but overjoyed to keep the whole box. One little box can change a kid's life [maybe even their family, or village]. Like World Vision there is also lots of other ways to support Samaritan's Purse and the work that they are doing throughout the world. Highly recommended.
And maybe not as widely known about, but is one of my families favorites, Metro Ministry. Growing up my parents always sponsored a kid from the Bronx. So much poverty and devastation within our own country and the sidewalk ministry run by Bill Wilson, once a kid from the Bronx himself, has made a huge impact. During Christmas they do something similar to shoe boxes, but instead you fill a stocking. I remember one Christmas we made stockings out of felt and were so excited to fill them!
"Rejoice always, pray continually, give thanks in all circumstances; for this is God’s will for you in Christ Jesus." -1 Thessalonians 5:16-18