[decafninja]

I'll echo the advice of grinding as much leetcode as possible. As someone else mentioned, as a bonus, try talking and explaining (to yourself, or if possible someone else) while you solve it.

...that said, mock interviews or talking to yourself doesn't prepare you for the real thing as well as the actual real thing. The next best thing is to actually go out and interview at every possible opportunity. This can include companies you aren't really interested in.

Is this ethical? I'm not sure. I tell myself if a company can put together a compelling offer, I'm always open to it even if I initially may have no interest in them other than for the interview practice.

Of course, even this is not a fully realistic simulation. You naturally will be more relaxed when you're interviewing at a place that you don't really care about vs. when you're interviewing at a place you really want to join.

Also levels of difficulty varies from company to company too. You'll probably get a more difficult interview at say, a FAANG, vs. some generic Fortune500 non-tech company. That said, I've been thrown leetcode hards at no-name companies.