I am still rather busy, so sorry for the slow down of photography tips.
Birthdays can be tricky, especially if you are doing it in the evening or going for the candles in the dark room look. But this is where your understanding of your camera, ISO, F-stop, and shutter speed all come into play. If you understand those things then you should be able to pull off some decent birthday cake shots.
But before that, take a moment to look around and scout the best angles as well as look for foreground and background things to remove. I am talking about trash cans or maybe the table needs another wipe down. Also look for the best angle. Usually, the person or people hosting the party won’t mind adjusting a little to help you get that shot. A little though, don’t push your luck too far. Find out where they want to have the cake and work from there.
Finally, know you will be working in the dark and with a low light. That means higher ISO, wider F-stop, and slower shutter speed. That also means less movement on your end. You want to keep that camera steady. A tripod might come to mind but that may not be realistic depending on the number of people around. Your mileage will very as not all brands are uniform thus a good understanding of your gear is what matters the most.