Do one book at a time, starting at the beginning, until you can solve each problem in a few seconds. Then turn the book upside down (then sideways etc...) and do it again - it will be a bit slower at first because you're making your brain remember the technique rather than the problem. Once the book feels easy, do the same thing with the the next one and work through the tesuji series in the same way (at the same time is good). If volume one proves to be too hard, start with an easier book and work up to Lee's books. I'd be very surprised if you're not dan level by the time you finish going through volume four of Lee's life and death in this way.

No matter how much some people want to deny it, the truth is that the opening really doesn't matter and your middle game strategy doesn't even have to be that good (and endgame never happens) if you can just kill lots of groups and live everywhere. This is totally achievable, even at the low dan level. But this isn't a magic bullet, it takes time, consistency and hard work acquire the skill. You can easily build a well balanced game on these strong foundations later.

The important difference between these problems and the ones you'll get from tasuki (and other places online) is that the Lee Changho books have very high quality solutions (some of the best I've seen for the most part (excluding a small number of editorial mistakes which exist in most Go books). I know some people have other views about this, but I can't stress enough how important it is to have good quality solutions. If you value your time at all, you want to learn the strongest way to kill, the most ironclad way to prevent ko and the most efficient and profitable way to live the first time round. Those 'small' advantages in technique are what allow you to overpower your opponents and become a stronger player. For most amateurs they're enough to decide many games. Imagine if you could've prevented that ko, or pulled a ko out of thin air in your last game. Imagine if you knew how to play to minimise ko threats, while your opponent let them pile up like a bad debt.

If you learn from problem sets that have weak solutions you'll only learn to play weak moves. You'll spend more time unlearning all that later. Even worse is the school of thought that tells everyone that you don't need solutions. That's partially true when you already have a comprehensive understanding of shape and are strong enough to read a problem out completely. When I do easier problems I often don't need the solutions anymore. However, when I do hard ones, I still get some problems wrong, no matter how hard I try. When I get them wrong, I usually learn a new tesuji or something else to watch out for by looking at the solution. It finds the weaknesses in my reading and fixes them. If I didn't look at the solution I'd continue in the naive belief that I'd solved the problem and would keep using my inferior moves.

Showdown today! Clash of titans, speedchase vs rberenguel!

Remember 9d is stronger, sure, but his one stone is still just one stone, it doesn't have 5 liberties, and his group still needs 2 eyes to live

On the Go board please remember there is such a tendency: the more passive you played, the more the opponent will gonna ask, exactly like how terrorists work against civilians. So the only way is to say no from the start, otherwise there is just no end

I also loved these quotes in the review:

I have to clean my game from passive moves, but I find it veery hard. Suggestions?

I also recovered Graded Go Problems for beginners, vol 3 from my parents' house. I think it can quite fit for my current level to pick it up again