I got myself an profile at calckey.world where I post screenshots of a chat of a game. But I am not getting much visibility.

Is there any better instance I'm supposed to go to?

I don't think you can. Any federated server will show your posts, and you cannot scam a karma system that doesn't exist.

Not familiar with the instance or the underlying software, Sharkey (other than being a fork of Misskey), but have you tried posting to communities and/or adding tags to your posts? Those can broaden your reach. And if Sharkey doesn't support communities natively, you should still be able to post to communities by mentioning the community but swapping the ! for an @, e.g. @fediverse@lemmy.world instead of !fediverse@lemmy.world. However, do mind the first paragraph of a microblog post sent to a community becomes the title for the community, so try writing something that could work as that instead of something potentially spammy even if normal for microblogs.

Also, popularity is something you build up, so patience and resilience are the key.

yea I agree, posting to Lemmy communities has way better visibility than anything else in the Fediverse

microblogging platforms can subscribe to and post to Lemmy communities, people should do it more often

About subscribing to communities on Mastodon and the sort, I'd advise against that.

Mastodon's main solution to communities since they don't have a native community feature are bots that boost anything posted to their respective communities, including any comments, making your feed a spam hell if you follow the community bot.

Their other solution, and what I'd suggest instead, is to follow the hashtags equivalent to that community, usually what comes before the domain in the handle, e.g. #fediverse for fediverse@lemmy.world. When a post comes from a community, Mastodon adds a hashtag to it with that logic, and thankfully it doesn't for any subsequent comments to the given post.

Example of the community being turned into a hashtag on a post:

I use it for small communities and it's fine, I don't mind seeing a few comments. Also that might just be Mastodon, what about the other microblogging platforms?

Following the hashtag is great if someone else on your instance is following the community. But without anyone following the community, the posts just don't get federated at all, and the hashtag is worthless.

Mastodon adds a hashtag

Actually Lemmy does it, not Mastodon

Actually Lemmy does it, not Mastodon

Ah, wasn't aware

But I am not getting much visibility.

I'm afraid that's just how it is. Tags aren't very popular among Mastodon users in my experience so they don't help much either (but I still recommend adding some tags). Literally the only thing that helped my posts getting seen is a boost from some popular Masto person.

Awh :(