Domain names are fairly easy to buy, but there are few gotchas. A lot of them are only learned by experience. So choose your domain name provider carefully.

1. Not all domain name registrars support all features. For example, Microsoft makes it easy to buy domain names, but they are only resellers and don't support all features (like advanced records).
2. Domain name transfer essentially renews your domain for another year. You lose the term that you have already paid for.
3. Transfer can take 1-2 weeks depending on the providers involved. Make sure you plan for this.
4. Once you enable transfer at your existing registrar, there is no going back. It also disables your Whois privacy because the real information is needed to actually conduct the transfer.
5. Always get Whois privacy. Bots harvest any public information and you will get a lot of spam.
6. Research the reputation of your domain registrar. Sometimes things do go wrong and it is nice to have good support. Good support doesn't come cheap. So avoid bargain-basement options.

Hope this helps someone (may be me!) in the future.