A hugely under discussed aspect of alternate picking is that of picking hand imbalance and the trouble it can cause.
Alternate picking is when notes are executed by the picking hand in an alternating manner - a downstroke followed by an upstroke followed by a downstroke and so on. For whatever reason, players often tend to be far better at downstrokes than they are at upstrokes. And, if one picking direction is favored then a picking imbalance will be encountered.
Let's dive right into exercise No. 1 to combat this. Exercise 1
Take this chromatic exercise. It's 4 repeating notes played with alternate picking. Accent (pick hard) every downstroke. And now... Exercise 2
Try the exact same thing but accenting every upstroke instead.
Did you find one exercise easier than the other? Whichever one you found to be a little harder - practice that one far more than the other. Working on our weaknesses makes us strong, and in the context of these 2 exercises, working on our weaker pickstroke will bring us balance.
The other area of alternate picking which is prone to imbalances is string crossing (playing a note on one string and then switching to another to continue playing). There are 4 ways to cross a string: Outside picking away from you, outside picking towards you, inside picking away from you, and inside picking towards you. Here is a graphic to explain what I mean:
String crossing is the biggest hurdle when it comes to fast, accurate, multi-string picking runs, and all 4 of these string crosses need to be mastered evenly. If even one of these aren't as good as the other 3 then you will be imbalanced and severely restricted.
And so I designed a short, repeating exercise to address this. The exercise includes all 4 string crosses. You will feel what I mean the moment you try it! Exercise 3
Here is the video for the final exercise with in depth explanation: