Brute-force + implementation.

Most tags on codeforces specifically state one algorithm that is used in order to solve the problem(for example fft, 2sat), or a category of problems(like the ones solved with a greedy algorithm, or with dp).

In theory I think that the best tags for a complete beginner are brute force and implementation.

However, as soon as you begin to learn more advanced algorithms or ideas, or after you solve enough brute force and implementation problems, you have to try problems with more interesting tags(like dp or greedy).

From this point on, I feel like the tags aren't doing their job, for multiple reasons, for example: they sometimes are incomplete and also are usually modeled after the author's solution, even if it is not the only solution, so you might have a good idea that could potentially lead to a good solution, but then look at the tags an think that because it isn't in the tags, your solution is bad.

I think that the best way to continue improving at competitive programming using this website from this point on is just by participating in the contests and possibly by simulating contests, because they usually have a pretty good composition of problems, and of course, after you participate in contests a good practice is to think about the problems you didn't solve for about one hour and than look at the editorial.