Beginner's mistakes

Who better to write about mistakes than a newbie knitter like me who has made so many? Here are a list of beginner's mistakes that I've made, and if you're new too, you should watch out for:

1. Accidental YO: In My First Circle Scarf there were many holes because as it was a ribbing pattern, I had no idea about moving the yarn to the front if its a purl, and to the back if its a knit. I searched up why I kept ending up with holes and extra stitches, and after starting over a couple times (or just kept soldiering on because at the time I didn't know how to fix mistakes), I finally realized this mistake.
2. Not pulling off old stitch: This was mentioned already in My First Project EVER where I didn't really understand knitting, and just had a vague idea of just going through the motions. Its another way where you end up with more stitches than you should.
3. Right sizes: A lot of projects were a lot tighter or looser than they should've been or smaller because I used the wrong knitting needles or yarn type. It's actually very important.  
4. Twisted stitches: This is for knitting in the round. When you connect the stitches together, make sure they're not twisted, and they all line up properly ... because if you don't you'll realize too late, its not a fixable mistake. The only thing you'll be able to do is rip the stitches out and start over.
5. Pay attention: I like to knit while attempting to watch TV or talk (key word: attempt because knitting takes a lot of focus for me. I'm pretty jealous of those people I see on the bus whose fingers are working away while they're doing something else and don't even need to glance down at what they're doing.) However, sometimes when I'm supposed to purl my knits or knit my purls or whatever, I do the opposite accidentally and have to go back and fix it (I almost feel like I spend more time undoing stitches than actually making them). On a related note, learn how to read you work! It saves a lot of headache. A noose means it was a knit stitch and a horizontal dash means it was a purl stitch.. and an unintended hole means wanting to cry.
6. Slipped stitches: This is can also be related to point 5, but sometimes it happens where a stitch fell off your needle without you even noticing even when you could swear your blood sweat and tears were all focused on the act of knitting. Anyway, learning to pick up slipped stitches so that its less of a big oh shit moment is a must.
7. Leaving a tail: For long-tail cast-on, for God's sake, leave a long tail. I mean, its not that bad having to start over since its at the cast-on, but it is annoying. Especially when you're casting on a ton of stitches.
8. Count stitches: Not sure if pros do this, but if the pattern calls for CO 140 stitches, after you cast on, count the damn stitches before you just jump into knitting. Because after the first row, and you realize something is not quite right because you only CO 139 stitches you're going to have to start over. I'm pretty paranoid and count twice because I really hate starting over.

I'm pretty sure I made way more mistakes than this, but this is all I can think of right now in the early early morning. Feel free to add to this list as I'm sure I will be doing as I continue to learn new things. Remember, mistakes are a good learning experience. Just make sure not to repeat them .. which should be point 9 for me as I am guilty of not learning from them the first time.