This is as simple as it gets. Helping those in need is the fundamental principle of community service.
Reach Out- You'll need to contact an organization that administers blood drives (Red Cross, Carter, etc.). Find out their specific requirements and needs, then assess if it'll be possible for you to organize the blood drive.
Seek Help- It takes a team to pull off a blood drive, so find 5-6 others who will help you. The volunteers will need to help you find donors and manage the drive so it runs smoothly (most blood drives abide by a strict schedule).
Get Donors- Get the word out about this blood drive using posters and social media. Have potential donors sign up for the drive according to the organizations requirements.
Help Manage- The organization you're working with will do most of the work the day of the drive, but you'll still need to help situate the donors and provide snacks/water for them. As the donors come in, make sure they fill out all required paperwork and have them seated until the organization is ready to take them. After they get their blood drawn, make sure they sit down in the waiting area for at least 15 minutes to check to see if they're fine.
Clean Up- Take everything down and help the organization pack up. Don't forget to thank them for helping you out.
Make a List- Find out what local shelters are in high demand of. Hygienic items, socks, and seasonal clothing are the most commonly demanded donations.
Get the Word Out- Make sure this list is visible everywhere, people need to know what they should donate.
Stockpile- Collect these items and store them somewhere safe. Remember to thank every donor for their help. Post on social media and make flyers to put around your school/office.
Ask for Help- Get a few volunteer friends who are willing to help you with this project. They need to help you pack the donated items into boxes.
Buy Boxes- You'll need small sized cardboard boxes that can fit one of every item on your list.
Package- Once you finish your item collection, gather your volunteer crew. Put one of every item into the cardboard boxes and tape them up.
Deliver Them- You can either drop these care packages off at your local food pantry, or you can personally deliver them to the homeless in your area.