i am crappy at initiation; that being said, here are some simple rules of what to, and not to, do.
Do not say anything in a first contact meeting that you would not say to an absolute stranger, when you have just knocked on the door to their private residence.
That is exactly what you are doing in our inboxes! You have knocked on our door, in our home (more of an apartment complex or gated community), to say hello to us.
Read the profile, look at the collar brackets, look at the role and gender preference. Do not use any forms of endearment like sub, baby, slave, etc. Especially no degrading ones until you know you have that consent.
(i do not, nor will i ever consent to being degraded. i have an intense limit for that, yet have been called things in my inbox by people i don't know far more than i would like to admit.)
When hunting cougars ... i would not suggest in any way of referring to yourself as youngin...
"Age is just a number" is NOT the correct response to "i'm sorry, i don't [date, dynamic, hookup etc] in your age bracket"
Just please take the rejection. You are not going to change our mind, you are waving a red flag. We will remember that.
Here is something of a basic example of a mid to good first contact, it's generic but at this point generic is better than the desperate vile trash we generally get.
Heya [screen name], how are you today! I saw you [insert where you found the profile/screen name] and you (or your profile) caught my eye because of [insert reason you reached out]
My screen name is this, and I am [insert cool NOT sex related thing about you here]. I would like the chance to get to know you further, in the hopes that this could lead to a [insert your actual, honest intent here, we can smell your bullshit most of the time]
Would you be interested in continuing this conversation?