Ah, love letters! Those little notes that lovestruck teenagers write to each other, particularly in the instance of unrequited love (q.v.), only to discover that they find their way into the hands of the class loudmouth and are read out in front of all your friends, resulting in total humiliation.
Oh, just me then.
I have simple advice for anyone considering writing a love letter – don’t bother. If you can’t say what you need to say to the person’s face (or by telephone if there is distance involved), then it probably isn’t worth saying. Aural always beats a piece of paper (stop it!).
Once again, it is important to be wary of the people of France. They might send you a French letter. This is yet more evidence that the French are confused, although it has to be said that receipt of such an item probably suggests that the relationship is progressing well. Or that you have VD.
Of course, if you have an e-relationship, then different rules apply. In an e-relationship, much of the communication is textual within the constraints of current technology. Since it is the interwebnet and anything goes, then you may use whatever language you wish to in your correspondence – the more suggestive, the better, since this is the web and we have a seedy reputation to maintain.
Interestingly, in the course of researching this entry in the Lexicon, I found this "helpful" webpage on the subject of writing love letters. I found the list of useful words for inclusion in love letters to be particularly, erm, useful:

• Alluring
• Kisses
• Embracing
• Voyage
• Blossoms
• Stars
• Angel
• Lover
• Elation
• Sensuality
• Heart
• Giving
• Darling
• Rose
• Absence
• Seeing
• Tasting
• Touching
• Holding
• Caressing
• Memories
• Content
• Lascivious
• Beautiful
• Gorgeous
• Vision
• Privileged
• Adoring
• Velvet
• Rainbow
• Happy
• Passion
• Innocent
• Dreaming
• Delirious
• Temptation
• Complete
• Desire

Now, I haven’t set any homework for you, my darling Uborkans, so far in this course. So, by tomorrow, I’d like you all to write a paragraph from a love letter that you might send. Be sure to include at least three words from the list above. For example:
"I have complete memories of tasting your passion fruit flavoured Angel Delight".
Please leave your homework in the comment pigeon-hole in time for marking, children!