The only vaccine the Democratic Republic of Congo requires for entry is Yellow Fever within the last 10 years, but there are plenty of other choice diseases there! One of them requires 2 doses administered across a period of months. When I told my companions I was going to skip that one because I wasn't planning on sharing any needles there, I learned that you can get it from a blood transfusion and that it's a particularly nasty disease. I signed up for that one right away.
The vaccines with Live virus have to be spaced apart so it requires some planning. Even a booster for polio is highly recommended. Other vaccines are only considered good for a few years. For polio and a few other "outdated" vaccines in doubt I had blood titers done. Turned out I have good immunity in all the titers, so I was spared subjecting myself to several of the shots. Some of the new shots I needed were not available locally but only at a "travel vaccine" place, where they try to sell you everything else imaginable but also give excellent information. And these shots are expensive! Then there are various options for malaria pills, also highly recommended.
The other two travel-preparation tasks were getting our visas and airline tickets. Unless you live in Wash DC you can't just trot over to a local DRC Consulate. We had to trust FexEx with our passports, but the passport services place worked out fine.
Last thing we are sweating is airline tickets. Flights are a real roll of the dice these days. Last few times I've flown I'd been trotting at full speed for one gate only the receive a text of change of gate and had to trot back the other way. What's less amusing is missing a connection due to a delayed flight. We are trying to converge onto one flight out of Paris to arrive in Kinshasa together. So far they have changed my flights three times without regard for the amount of connection times required. So far this has been the most complicated part of the planning.
I was 12 years old the last time I flew to the Congo. This was in comparative luxury on Pan Am with my family, my sister's parakeet and our large standard poodle. My mother the nurse had practiced drugging our dog to make sure she had the right dose for sedating him to travel in the belly of the plane. But apparently during the longest leg from New York to Africa the sedation took the opposite effect on him. He went wild, shredded his favorite blanket, bit his way out of his kennel and ran loose, terrorizing everyone who tried to catch him. For the remaining legs of our flight, my father arranged for him to fly in the cabin with us. Joë did not make a peep and stayed under the footrest area (larger in those days!)
For the return trip two years later, my father made sure Joë could travel with us in the cabin. Unfortunately my sister's parakeet, who was already quite elderly, had died in the Congo. The only thing I remember about the return flight was feeling my heart literally break upon take-off. Physically very painful, unlike anything I've ever felt before.