Adding だ copula to casual sentences

[sirvine]

Every grammar textbook told me to add だ to sentences like 猫と遊ぶのが好き(だ). But when I actually followed this advice, my friends and family mocked me and said I was talking like an old farmer.

Obviously, you need to use だ as copula in some grammar scenarios, but I’m always slightly undecided about where. Does anyone have a nice, simple way to keep track of cases where だ copula is required/appropriate that won’t cause me to sound like 農夫 who just arrived in the big city with a bindle and a pocket full of magic beans?

[Leebo]

I haven’t heard anyone say it sounds like that, but it’s just more blunt and direct than necessary most of the time. I generally only end sentences with だ when I’m trying to emphasize that aspect.

[sirvine]

That’s helpful. Thanks!