That does come with experience. Once you knit a LOT and you really understand what it is that your weaving you will instinctivly(sp?) know how to TINK...and for the rest there is KH!!! The lifeline is a great idea though. I used one when i made my first cable and lace baby jacket because i knew i wouldn't be able to fix it if i screwed it up, but I ended up screwing it up on a totally different level and you know I would NEVER have been able to fix it without the help of people on this site. If you need help just explain it the best you can on here and you will be so surprised at how many people will understand and be able to help. We have all made EVERY mistake there is to make and will probably discover and make totally new mistakes of our own (I think that's what I did with my baby sweater). Don't you dare be discouraged! The fact that you can recognize a mistake is a skill on it's own. Keep trying and WE CAN HELP!