I think the standard way to improve your poker skills preached by most players is: watch training videos, read poker books and contribute to poker forums by asking questions. Those are all great methods of improving your poker skill. For newish players or players who have just started winning, this is a great strategy. You will pick up a lot from watching videos and talking on forums. However, once you go past that stage and you want to get to an elite level, you need to go outside the realm of popular knowledge.
At one point I purchased over a million hand histories and used a popular player look up tool to find the biggest players at that limit. I then looked over the hand histories that reached showdown from these players in my poker tracker. What I did was analyse the why. I looked at all the decisions they made. I then Isolated the decisions which were different to the ones I would make and then considered the “why.” This has helped me modify my play. I have to accept that the people winning the most at the limits above me, know what the hell they are doing, so I figure it out, and copy. I personally need to do this more and when I make a foray back into playing again this will be the first thing I do. This tip really is golden.
I urge you to make some poker friends and try to sweat some of them playing. By asking questions in real time it's a learning experience for both the person playing and the person sweating. Ideally you should try and sweat someone better than you and pick their mind. If you can't find someone better than you because you are new or are an unknown player, I would suggest paying for a coach. If you have a few friends on AIM who are a similar skill level as you, you can both learn some stuff from each other and hopefully become better players.
If you are a nl50 regular (reg) and have nl50 reg friends, chances are you will be a nl50 reg for a while. If you are a nl1k reg and have nl5k reg friends, chances are you're on the path to improvement and will join your friends soon. It's ok having friends who play the same limit as you, I have tons of friends who play nl200. I don’t want to sound arrogant, but heck, I am… Most of these players are ok but definitely not better than me. By sharing hands with them I’m not going to learn anything new. I have maybe 10-20 players on AIM who play higher than me who I talk to often. I tend to respect the advice of these players more and some of them have the ability to think more comprehensively about all of the variables. What do I advise? Try and make friends with regulars on the forums both as good as you and better than you. The better company you keep, the better you will get.
I have never been coached per se. I had a tilt coach for a small period of time and that was, LOL stupid. I also have gone through a few mid stakes coaches but didn’t want any more lessons when I realised they weren’t much better than me. If you are starting out at say nl50, nl100, nl200 a coach may be beneficial. All I’m going to say is that it hasn’t worked for me. There are lots of good and bad coaches out there so make sure you do your research. Get references and make sure they will tell you their screen name so you can check for yourself how good they are. Also keep in mind that being good at poker does not necessarily relate to being a good poker coach. Finding a solid poker coach can be gold - but spending a ton just to find the right one is a huge waste of resources.
Make a video of you playing, upload it and share it with your friends or post it on forums asking for a review of your play. Cumulatively, if you get hundreds of players viewing your video, they will likely spot some of your leaks. Take the criticism constructively. You may (or may not) be surprised at how many leaks other players will point out. Use these as fuel to improving your game.
I have had a decent amount of success with this. I have purchased or have had a friends purchase a great deal of premium poker content. From Bobo’s Bible, The Memoirs of aejones, CTS’s book, Let There be Range, Improva’s book, BalugaWhale’s book - Easy Game, etc. I have read them all. Most of the ones I mentioned are fairly decent and worth the money. It's okay to invest some of the profits you have made back into education. I would go as far as saying it's mandatory for any professional player looking to get better faster than the games are getting tougher. As a professional player your mind is your biggest asset, so it remains critical to invest in it.
Mentioned in my initial paragraph, training sites are probably the best value way to get better fast. I think once you get to a certain level, videos start becoming less effective. I have memberships to almost every training site out there and only wait on videos from the best players, most of the lower/mid roster of the sites players I cannot learn much from. Also, I only want to be open to listening to the concepts and theories of big winners. Not some 1 pt winning reg who thinks he can teach me how to play better.
One tip I would give you is to watch a training video on mute every now and then. I think I a lot of training instructors tend to gloss over the details, either on purpose or by mistake. If you look at a training video on mute and keep re-winding, fast forwarding over hands, you can do the analysis yourself and ask yourself, "Why?" before even hearing their reason.