Which decisions I make today will affect me for my entire life?

The decisions i make today will and can affect my entire life because of me not making the right decision. Some decisions i make right now i know i cant keep making the same decision as i get older. Only because I've made it once and wasn't happy with the outcomes as a teenager, some things never change. Wrong decisions i make right now while I'm still in high school are very important to me, I'm kinda bad at making decisions. But i know i have to grow out of it now because it may look bad on me through out life. They say your reputation follows you, but i don't think it's true. Sometimes I'll make a decision that i know is most definitely not good for me, my instincts are telling me its a bad situation and i shouldn't put myself thou it but I'll go ahead and do it anyways instead of just listening with my first mind. when ever i make a decision and i know it will be good for me i tend to second guess myself a lot. Making bad decisions happens to everybody at any age there's always going to be a consequence to every decision wheater it be good or bad. But there's a difference between learning when to listen to your instincts because your know your making a bad decision and just knowing that one bad mistake can completely put your entire life in jeopardy. Decsisons i make while im in high school are important to me because i want to graduate and be successful in life. I cant always do that by my decision making. I need a little more help and a LOT of focus to get what i need done when making decisions. Bad decisions are the major decisions. Ignoreing the right thing to do and doing the wrong is also another issue i have when i comes to decision making. The older i get i realize it takes just ONE bad decision to ruin my life for good.