The secret sauce to achieving a trending post: completely serious advice from an entity (possibly human) which has achieved this multiple times and is therefore qualified to make up a not at all crankpot recipe for success. Presented for the benefit (yeah, let's go with that) of those misguided souls who might view trending status as a mark of success.
First, you need to spend at least half your writing time thinking carefully about the title. This is make or break. It should feel off-handed and not over-wrought, so it's worth taking the time to craft just the right feeling of casual carelessness.
Second, keep it short. It should be long enough that people have to click on it to read the whole thing, but no more than, like, three words below the fold. No one reads more than 6 lines of anything, and if they see it's more 10 lines they won't be bothered to read it at all.
Third, choose one of these subjects:
A) Ermahgerd, I'm so heartbroken right now. I've creeped around my crush for 5 and a half years and now they just hooked up with someone else, who is clearly a **** because they aren't me. Can you believe when I bared my heart to them they called me a creep!? Ha! They can say that to my face as I imagine them doing ***** things while I ******* in a bathroom stall on campus at 10:38 AM! Except I'll make sure to leave that part out of my poem. I must cast myself as the hopeless romantic who has been unreasonably cast aside, not as the fedora-wearing, ukelele-playing, possibly ginger, neck-bearded, beta-male, **** addict I really am. Then the social validation will compensate for my hand-chaffed *****, and I can hit on all the poets pretending to be teenage girls.
B) orange man bad! hate is good if directed at orange man! anything that make orange man look bad must be true!
C) Girls, ya'll need to love yo' self! He ain't worth all that anyhow!
D) Flowers are pretty, and mountains too! Also, the sky, and water. Everything is whimsical and quaint!
E) Everyone here is awesome! It's so awesome to be a part of this amazing community! Really, present me your boots and *******, because I'm in a licking mood!
F) I can't believe I fell for a **** again! I mean, I didn't change anything from last time around, and I jumped straight into bed with the first charmer that came along, but still: I deserve better than this!
G) Guys, I'm totally gonna **** myself. But, seriously, all the rest of you have everything to live for, so please keep on! I love you all, especially you ditzy girl that posts positive things on literally everything, which is why I am going to leave you all with the painful memory of my death. Because I, uniquely, am qualified to **** myself justifiably. No one in history as suffered as much as me. No, the Holocaust doesn't count. Not the Bataan Death March either. Also, slavery, trench warfare, or atomic bomb fallout
H) I'm, like, totally trans, everyone! Aren't I so special!? Yay, me! Why am I not happy yet?
Fourth, post between 9 and 11 AM Eastern time so the US audience actually sees the post before it's lost to the ancient history of 3 hours ago. This might be the most important tip.
Fifth, comment on other people's poems. You don't have to be meaningful. Just sound vaguely positive. People are here for validation, not growth. If you give them a dopamine hit then they'll probably return the favor in the hope that it will become a circle ****. The internet is the wrong sort of digital for a circle ****.
Alternately, you can write caustically, vindictively, nonsensically, mockingly, and/or parodically, then post at random times of the day, and still randomly find yourself trending, which is a legitimate accomplishment for artwork like this.