That Which is Worst Should Be Practiced Best

If one of your songs is weaker than the others, it should be practiced more than other songs.
If part of one of your songs is weaker than the other parts, it should be practiced more than other parts.
If some part of your playing technique is weaker than others, it should be practiced more.

You want all of your playing to sound good. All of your songs, every part of each song, all of your tricks and techniques, your bells and whistles.The only way that's going to happen is if you make the harder stuff... well, not so hard. If something is more difficult to play, that means it's going to require more practice.

This is why I say:
That which is worst should be practiced best.

(It's probably better English to say "most", but it somehow sounds more poetic and memorable this way).

The challenge lies in convincing yourself to do this. We want to have fun on our instrument, so who wants to spend lots of time on the really hard stuff, right? The truth is, you will enjoy the instrument far more if you do spend more time on the difficult parts, because those are what will really change your playing for the better.

When I was learning ACDC's "Thunderstruck", I spent about a year-and-a-half on it. I could have spent far less time on easier songs, but I wanted to improve my overall playing ability on the instrument. And boy did I ever! Learning that song catapulted my playing ability to greater heights than I ever imagined possible.

I have seen so much success following this philosophy of practice that I generally never learn a new song unless it provides a challenge, because I want to keep getting better, and because I now have the faith that I can master any song I practice. And that kind of faith is a bonus from practicing this way: you will become confident in your ability to learn whatever you want to learn, and it will make practice far easier.

So remember...
That which is worst should be practiced best.