As soon as you have selected a product to work on you should check if the domain is available.
If it’s available you should also do a search in the US trademark database to ensure there’s no trademark for this domain.
We had kept some nice and short domains and it turned out that several months prior to our domain registration another company had filed and had a trademark approved for that. You don’t want to be dealing with legal issues especially if it’s a startup
You can get your domain from your hosting provider but I highly recommend that you use one company for domain registration and another for hosting.
Some people prefer to use CloudFlare, others NameCheap, Domain.com.
Most registrars will give you reduced prices to register a domain with them or to transfer one to them but the renewals will be a big higher. Some registrars even go 50-80% higher than the original (promotional) domain registration price.
If you’re using NameCheap and have accumulated lots of domains you need to do two things.
1) check how many domains you have.
There are different tiers and you can get reduced prices for domain registrations and renewals.
You have to contact support for the reduced pricing to be enabled for your account.
https://www.namecheap.com/domains/tier-pricing/
At the time of this writing the prices are as follows
2) Enable 2 factor authentication and copy your auth codes in a secure place.
This will ensure that your account is secure. Make sure you copy the authenticator codes to another phone or tablet just in case