How to remind a tenant to pay rent?

[Dirk S.]

Hi all, the tenant never had an issue and paid on time for 2.5 years. Now its the 5th and the rent was due on the 1st, with a 7 day grace period and $30 penalty thereafter. 

I need help wording a friendly reminder. I dont want to give too much leeway, but given her history, I think I want to be friendly but professional. What should I text (email, call?  ) her? 

[Al Bryant]

Great to see the responses here. Hoping I have this problem soon...as I have 0 properties today :-D I'm working on it though.