Grant read access to my SQL Server database to all future SQL users
To add on my comment, you can create a trigger on a database level and add user to desired role automatically when you create a user. You can add a custom one, but for example sake i added db_datareader.

Example :

    create trigger tg_AddUserToRole on database after CREATE_USER
    as
    declare @LoginName nvarchar(30)
    set @LoginName =  (select EVENTDATA().value('(EVENT_INSTANCE/ObjectName)[1]','nvarchar(30)'))
    IF EXISTS(select 1 from sys.sysusers where name = @LoginName and  issqluser = 1)
    exec sp_addrolemember 'db_datareader', @LoginName