The ability to create original shitposts that don't recycle existing objects and concepts makes you a certified shitposter.
Examples of recycled objects: Bernie sitting, Dancing cat- she is not dancing, Forgor 💀, Whar 💀, Rembr 💀, Mind-blown emoji used in sarcasm, furry characters.
Examples of recycled concepts: Responding absurdly to tragedy ("My uncle died in 9/11, he was a pilot", Mind-blown emoji used in response to own child's death), Meme-man-type spelling errors, misunderstanding similiar-sounding words as pop culture references (Messy ink pen = Jesse Pinkman), pedophilia jokes, "Drake the type of guy...", racism jokes.
Creating self-sustaining memes is the best way to start off to become a certified shitposter.
Here is an example of one:
[Picture of a Shrek horse that says "IBUPROFENDO"]
Creating new concepts for shitposts might be difficult, remember that it's not one person controlling what is laughed at and what is unfunne. Change comes gradually, old concepts inspire new concepts.
Taking the above-mentioned Ibuprofeno as the example: Shrek became an integral part of pop culture, and incidentally, shitposting communities.
Older shitposts talked of worshipping Shrek as god, building a religion around Shrek or admiring Shrek's handsomeness. Ibuprofeno takes Shrek and creates a banbana-type shitpost, which doesn't even require the viewer to even know Shrek for it to be laughed at.
However, using an old object in a new popular trend is fairly easy. You would be considered a shitposter if you do it consistently, but you won't be certified.
Imagine Bernie sitting on the "Chinese spy balloon". It requires no work and remains mildly funne; the object was already there for use, and popular culture provided it's own situation.