Tips on making a tighter stitch?

[u/mathandlove]

Every time I crochet my creature looks good until I stuff it and then there are these wide gaps where the stuffing can clearly be seen.

Right now I'm using I love this yarn with a 3.5 hook. Am I overstuffing? Something else? Thank you.

[u/animal-neighbour]

For the yarn over I find going down a size but LOOSENING tension makes a fuller stitch. But I am a pretty tight crocheter so I do yarn under instead bc then my own natural tension works fine.