What goes into an offer on a house?
The price, earnest money, financing type and down payment, closing date, contingencies (inspection, appraisal, financing, home sale), any seller credit, what is included, and a deadline for the seller to respond. ListingCraft for Buyers puts these into an offer package you send to the listing agent, who then prepares the purchase agreement.
Skip personal "love letters" to sellers. Many agents discourage them because of fair housing concerns. Let your terms speak for you.