Great advice so far, key points...be specific, be direct and be concise, there are lots of creeps and flakes txting these guys all day long and wasting their time. They will know you are “legit” and you will therefore be most likely to get their attention if you follow these rules.
My first txt is usually “hello is this (name) from RM? Jack here. Very interested in your profile “. I like to confirm I have the right person/number before giving a lot of other details away.
Also if you want maintain your privacy set up a google voice account for this purpose - keeps all this separate from your “real” cell number. You can download the google voice app to your phone and txt from there.
Have fun