I see random sales pitches coming from strangers in their first ever messages. It's sort of funny, you just add someone to your friends list, you don't bother to introduce yourself, you add no value to the conversation, build no relationship, NOTHING.
How can you expect them to buy your product/service? Why should they?
It's like asking a random girl on the street to go on a date with you. What would happen next?
Don't SELL a service, SOLVE a problem.