So I know that Japanese tend to just skip over certain particles in casual spoken Japanese. Naturally you shouldn't do that if you're writing an essay or taking an exam but can you do it when you're writing informally? I'm not really advanced enough to read comments on YouTube or tweets and things like that to notice whether they do it or not
I unfortunately do not have time to go into examples, but my general advice for casual speech is to not use/break rules like this yourself unless you have seen it used enough to get a feel for it. Not all particles can be dropped "safely", so it's not as simple as a "particle = not necessary".
