I personally find that (proactive) lifelines are the easiest way to undo any knitting mistake. For beginners who are afraid to knit because of not knowing how to fix any mistakes that could arise, it is especially handy.
You place a ‘lifeline’ into your knitting every so often, as you knit, in anticipation of making a mistake. Then, if you do make an error, you can easily unravel your knitting back to where you placed the lifeline, and resume knitting from there.
The downside with this sort of knitting ‘fix’ is that you have to keep placing them into your work at regular intervals, because if you wait until you’ve already made a mistake, it becomes a lot more complicated to do (i.e. you have to do a reactive lifeline instead).
I hope this video helps you, especially if you’re a beginner who worries about what to do if mistakes occur.
Thanks for watching!