Unfortunately, I cannot participate here because I only receive sandwiches, I am not a giver. Speaking of which, I placed my order with you ages ago, what's the hold-up?
First choose a good sort of bread. Choose sourdough. If you can only get plain white loaf bread, don't bother.
Next, choose a cheese from this guide:
Assemble the sandwich and spread the outer faces with mayonnaise. Do not be tempted to get gourmet mayonnaise, use the cheap stuff. Fry at a slightly higher temperature than you would use for butter. Watch carefully and turn when the bread reaches the exact shade of golden brown.
You might think this seems like a lot of effort for a sandwich, but people are going to want to know how you got such beautiful toast.