One of the simplest ways to make your blog more professional is to buy your own domain. It isn't hard, and it isn't expensive. However, the benefits are endless. It will make your blog more professional, plus it feels so much better to say yourblog.com, instead of yourblog.blogspot.com. While I love blogger and it's platform, if you are seriously about blogging, you should make the switch.
To buy your domain on blogger, simply do the following:
Log in to you backend, then click on settings > basic > and then scroll down to where you see PUBLISHING. Click on "ADD A CUSTOM DOMAIN" (see picture below) and follow the instructions. Changing the domain this way should cost about $10 annually.
There are a two primary options to having your own domain with a wordpress template:
You can also opt to buy your own domain from Wordpress for as little as $18 a year when you sign up. Signing up for their basic hosting package also gives you the option of having your own domain. (https://signup.wordpress.com/signup/)
You can also buy hosting and a domain on your own, and then install wordpress in a one click download. I suggest using Bluehost or Hostgator.