I am a Do it yourself guy, but if you want to make this easy and get an optimal result, consider hiring someone to do both the aeration and also a slit seeding. The slit seeding puts the seeds at the perfect depth under the soil and saves you all the trouble of doing the work. You just have to mow, water and wait. If you do it yourself, it will come out great, just make sure you are up for the hard work. Using a spreader to get the seed placed is OK, not as good as a slit seeder but plenty good to do the job.
Definitely hire someone for the aeration though. It's a b---- of a job and the guys who own the big rigs are desperate to do as many lawns as they can, they will give you a great deal and you can find someone easily who will come out as early as is practical.