I've navigated this terrain a lot, and it's tricky because 'safely' means different things. You want sites that don't drown you in malware pop-ups, but also platforms that don't vanish overnight with your reading list. Places like Webtoons have mature sections, but they're heavily moderated—sometimes the steamier stuff gets toned down or removed. I've found some smaller, fan-translation sites through forums, but their safety is a gamble; my ad-blocker works overtime.
The real tension is between free access and supporting creators. Some of those 'free' sites hosting ripped translations feel a bit icky, you know? They pop up, get popular, then get shut down in a cycle. I've lost track of series that way. Lately, I lean toward official aggregators that offer a mix of free-with-ads and premium chapters—it's a more stable ecosystem, even if you have to hunt a bit harder for the truly adult content. Ends up being less frustrating in the long run.