If you enjoy planning and coordinating things—then I’d suggest the DIY option. With a good list of tasks to complete and deadlines, putting a birthday party together can be fairly easy and a lot less expensive than renting a party venue. Whatever you decide, do it early and stick to the date/time/place and the tasks/deadlines you’ve set.
Once you’ve confirmed the date, time and place, it’s time to work on the other important birthday details like the party theme, food and drinks, music (live, DJ or background music that plays continuously), and invitations. I’d suggest making a list of tasks to complete with deadlines. Refer to this list and check off tasks as you complete them. Think about everything you (or most importantly, the birthday boy/girl) would want to see at this party. If it’s a surprise birthday party, be sure to tell guests to arrive extra early so that you don’t have people showing up at the same time as the birthday boy/girl.
If you really want to plan this party with minimal stress, I’d suggest recruiting 1-2 friends to help you with the bigger details. Warning: Be sure you ask only trustworthy friends you can count on to get their assigned tasks done. Ask them to handle the food/drinks details, entertainment, invitations, and/or decorations. If you delegate some of the party planning details, you’ll have more time to get everything done and with a whole lot less stress than if you tried doing everything yourself.
Be sure to buy all your party supplies at least a couple days before the party date. You don’t want to be running all over town on the party date, so it’s best to buy stuff early, and don’t forget to buy a birthday gift! Keep your party supplies organized and easy to find on the party date.
On the big day, wake up early and get as much done in advance of the party. You should ask a couple friends to help you with the set up and ask them to handle some of the important chores to do during the birthday party, like preparing the food/drinks, decorating, getting the entertainment lined up, serving food/drinks to guests, and cleaning up. You don’t want to be barraged with lots of different chores to do before or during the party, so delegate some of these duties to a couple friends. You’ll have a much better experience if you can delegate, trust me.