See, I am basically the opposite of you, Ms. kitkat. I am the type of person who can make an immediate decision about something and so far I haven't regretted anything. I keep hoping sometime I'll mess up so at least I'll have a good story, but to no avail. I just got my monster half-sleeve started, and a few of the older people I've shown were all "THAT WILL BE THERE FOREVER" and I am all "okay yes that is kind of the point!"
When I was in high school the tattoo that I wanted the most was a Pixies logo. It was the P with a circle around it, and lightning bolts on the sides of it. It wasn't OMG I LOVE THE PIXIES SO MUCH as it was they were at the time this huge part of my life, and people from my hometown always related that band with me. I never got that tattoo, but I'm positive today that had I gotten it when I was 15, I wouldn't regret it now (I'm 22). Even if it was just that I really liked that band, it would have just ended up representing that time in my life.
Back to my monster half-sleeve though... I finally got it! There's still more work to do as the monsters' eyes aren't colored in, and the lines right now are all at the same weight. I felt bad for my tattooist though since I twitch a lot while being tattooed. Woo anxiety! I love that it's just outlines though- right now it looks like I'm just embossed since it's scabbed over so nicely.