A birthday spell can be a lovely treat to send to someone that you love and care about on their special day. You don't even need to share with them that you've done it - but more people are charmed than not by a little wish sent their way.
I find the best way to make a birthday spell 'sparkle' a bit is to make it as personal as possible. So if you know that the birthday girl or boy wants to travel this year, that they want to find love, that they need a bit of luck in a particular area, then include this for them.
Otherwise, I work on a basic spell I did for my best friend a few years ago. Feel free to adapt!
A birthday wish that's special to you
Is being sent this day
The turn of the year, the seasons it brings
May it assist you to find your own way
A year that will count
A year that will change
A year that will bloom
A year that will conquer
Be blessed and welcome all you deserve!