I too find myself hitting a ceiling at lvl 30 and upwards, I'm mostly hovering about 32/33-ish.
But then again, if I'm #57 on a list of 6000+, why am I complaining?
I think with any game, the results you get are roughly equivalent to the amount effort you put in.
My own personality is such that when I discover something new and exciting, I dive into it head-first to the point it almost becomes an addiction. Luckily, I still have a social life and a good marriage which I care more about than games, so it's not all completely unsanitary. But with any game, I always reach my own equilibrium at some point at which I'm better than most, but still worse than the best. I'm just not willing to put in the extra work to squash that little extra out of it. I like to go by feel and experience rather than trying to simulate the game to death. I don't want to keep track of the exact details of both my and my opponent's deck so I can make better decisions. I still like and choose to be surprised at times.
If you really want to get better (the best even), there's no substitute for experience and effort. If you want to beat theory on a regular basis, analyze his last 100 games. "But what's the fun in that?" Right, there is none. I can think of 100 other things I'd rather do. And if that means I'm not going to get better, than I'll just have to accept that. Some players have a natural talent for spotting complex patterns, while others are BMU-ing every single game and only trying something different if someone one these forums spots it and is kind enough to share it, for example the Apothecary/NV combo which was recently posted.
You really have to ask yourself with anything you do if the effort is worth the result. When all is said and done, it's still a game. And there are no shortcuts that instantly turn you from a level 30 player to a level 40 players, mostly because you need to beat those better players and they know as much ins an outs as you do. If you want to beat them, be creative. Pick a strategy and stick with it, see if it works. Sometimes, there will be a dominant strategy that you both have to go for, but try to spot that little detail which will give you an edge. Pcik up that +Buy early that you dream you'd had bought later on.
In conclusion, just accept that there are people better than you and try to be creative. Evaluate every card on every board from the context of that board. Bureaucrat is usually pretty worthless, but there's another topic proving just how good it can be. Don't get lulled into a false sense of security. Don't automatically think the more expensive cards are the best ones. If I'm going BM, I'd rather have a $2 Courtyard than a $7 King's Court. Try to see the complete picture, visualize what you need in your end game deck and go from there.
And of course, shuffle better than your opponent, that's really the best advise.
