I think something that is important to mention isn't as much about cubing and more about practicing.
Part of what I do is I (Professionally as a job) is to help people be more effective with learning as well as practice.
What I'm getting at though is that it's bothersome for me to see people say "Just practice". The reason this is ineffective is because if you practice wrong, you're actually holding yourself back. Classical pianists sometimes "tread water" instead of progressing professionally because they spend so much time playing the same songs over and over and getting really good at those songs, but reinforcing the bad habits they've developed and that holds them back.
I've talked to a few speedcubers that have a sub 14 average and asked them how they did it, and their initial response was "I just did lots of sovles" but then after a little bit of probing the REAL answer they didn't even realize they were doing:
They were turning weaknesses into strenghts. The thing that makes people so good so quickly is how fast do you acknowledge these weaknesses, and what do you do to practice and turn these into strengths?
So to give you a better, more applicable answer:
Let's break down your solves.
If you're doing a LBL based solve, you probably have the cross, bottom corners, middle edges, and then a 4LLL (So maybe Edges/Corners, and then PLL Edges/Corners)
Okay, so general tips or things that you can ask yourself while you're practicing. Like ACTUALLY practicing:
Cross:
Is it under 8 turns?
Am I pushing the cross to the bottom? Do I bring it to the top and then move it to the bottom? Am I being as efficient as I could be? Is it smooth? Am I able to execute it quickly (for me)?
I think the point here: Identify your weaknesses. If you find you have crosses that are 9-10 moves but you can execute them faster than a cross that is 6 moves, that's OK for now. Just realize that eventually, when you want to get even faster down the road, you'll have to start solving the cross with as few moves as possible *AND* have it be quick.
Then think about your bottom corners. How fast are your corner placements? Do you know the cases for placing corners and do you have any finger tricks that you can use while you do them? Have you started looking ahead? (While you place one corner, do you ALREADY know where another corner is and do you have already a plan in your head to place it even before you're done placing the first corner?)
Once you have that, what about your edge placement? Do you know a few algorithms for placing those edges? There's two "main" algorithms for placing edges without killing your corners, but then there are tricks you can use like keyhole that allows you to place corners if your edges are already placed, etc. (I say two main algs but there are WAY more. I just know most people tend to know two or three algs, for LH and RH for edges... Like if your edge is Top Front, and needs to be placed Middle Right... doing U (R U R') U' (F' U F), but then you can also do: Y L U L U L U' L' U' L' Y'. I don't have a cube nearby, so this is just off of my head, but folks please feel free to correct me on those)
Basically, without walking through everything with you, the point I'm getting at is this:
Identify the things you're not good at. It's not just enough to solve over and over. You have to actually CRITICALLY think about what you're doing so you can identify if you're doing something either wrong, or not as efficiently as you could.
Guitarists often think about practicing in their room as "Woodshed" where you practice your scales, arppegios, sweeping and such over and over and over, but if you're doing it wrong, you develop that bad habit. It's WAY harder to fix a bad habit than it is to establish a new, good habit.
So practice yes. But practice with a goal. Don't just solve all the time. (That doesn't mean it's bad to solve, but when you solve, solve with the intention of implementing a technique you've learned or want to practice using)
Make your weaknesses your strengths. You have to identify what those weaknesses are first, but that's why we often suggest looking at some of the better cubers and doing direct comparisons. I'm not a great cuber. I regularly get 18 second averages, the occasional 12 or 13 second solve with a personal best single non-lucky solve of 8.89 seconds. On the flip side, I also get 27 second solves, and I get REALLY bad cases where I freeze up with the cross and just can't get it in under 8 moves and my cross execution is horrible.
I frequently watch cubers though that are better than I am, and see what they're doing that I'm not and I try and adapt that to me to see if I can take a technique that works for them and make it my own.
That's why people take things like music lessons. You have someone who knows the "right" technique (Or the technique that has been widely accepted as being the most efficient) and tries to get you to adapt your own personal traits to match those that are "correct".
There's a large part of it that will be adaptation, (Making it your own), but the sooner you can start practicing properly, the faster you will get faster.
I look at Feliks Zemdegs, and only 2 years ago, he and I had the same averages as myself.
In two years, he's become EXTREMELY fast. *duh lol*
The thing I ask myself: What is it that he's doing that I'm not. Well, there's a lot of things, and some of it is time, but I GUARANTEE if you were to look at his abilities from when he was younger and back in early 2009 when he was getting 23 second solves... and see his "practice" routine, it would be working on things he knows he's weak at.
For myself however, I am almost 30 years old, and have a full time job, a home studio for music, a girlfriend, a house to take care of, and I travel for work a lot so I don't have the time to be able to commit to making my weaknesses my strengths. That being said, I have still been improving, just very slowly.
If you wanted to know about a specific practice schedule, something that I know is efficient and isn't specific to just cubing, send me over a PM though - again I do this professionally for adults with very short learning timelines, so while I might not be able to give you very very cubing-specific fixes for your technique (Which is something you should be doing on your own anyway) I can give you tips and tricks for being more effective WHEN you do practice
Also, look at this thread:
http://www.speedsolving.com/forum/showthread.php?27870-How-to-practice.
There are a LOT of very good points made here, and would be a great "mini cubing-practice bible" to follow.
The rest is being consistent. Consistently practice a new technique, and use it even if you don't want to. Eventually it will become yours but be patient. Don't expect it to work right away. Expect that you'll have to adapt it to your own style but it will happen eventually.
