For a SharePoint installation, this page recommends the following best practices and naming conventions for service accounts. In your deployment you many not need all these accounts. For example, if PerformancePoint will not be deployed then you will not need the PerformancePoint service account.
The account name is arbitrary. But, ensure the length of the account is within the character limits (see below: SharePoint and Managed Service Accounts and SharePoint Service Account Character Length) and the name is short while at the same time descriptive enough.
For SharePoint service accounts, do not create Active Directory Domain Services accounts that are Managed Service account or Virtual Service account. These two type of service accounts were introduced in Windows Server 2008 R2 and Windows 7. They are not supported in SharePoint 2013.
In Windows Server 2012, group Managed Service account (gMSA) was introduced. Those are not supported in SharePoint 2013, either. (http://blogs.technet.com/b/askpfeplat/archive/2012/12/17/windows-server-2012-group-managed-service-accounts.aspx)
SharePoint implements its own managed service account system in the Central Administration web site. You can use that to manage the SharePoint accounts.
For SQL Server services use Managed Service account or better yet gMSA, if using SQL Server 2012. MSA & gMSA is supported in SQL Server 2012. For example, you can use MSA/gMSA for the SQL Server Engine and SQL Server Agent. Use MSA/gMSA for SQL Server accounts that will not be used to login to the server. You can't use MSA to login to a server. The use of MSA/gMSA for SQL Server services is considered as best practice. MSAs are limited to a total of 15 characters (this does not include the DOMAIN\ part). The following provides a good reference on how to enable MSA (http://blogs.technet.com/b/rhartskeerl/archive/2011/08/22/sql-server-code-name-denali-adds-support-for-managed-service-accounts.aspx)
SharePoint service accounts (managed accounts) are limited to a total of 20 characters - including the Domain Name (for example Domain\SP_Name - total characters should be less than 20). This limitation is not imposed on SQL Server service accounts or SharePoint's Setup User Account (ex: SPAdmin). But to be on the safe side, I would still follow the 20 to 25 character limit.