How to not make silly mistakes in math?

Hi, I’m a high school freshman taking Algebra II w/ Trig (semester class). I currently have a 92 in the class and I want to get my grade up to around a 94 by the end of the year. I’ve found that I understand most of the material but I end up making mid-low As and high Bs in the class, because of silly mistakes. For example, on our last test (probability unit) I ended up missing 2 or 3 of the easiest questions on the entire test, which were simple probability questions (If I have 3 yellow marbles, 4 green, 6 red, etc, what is the probability of picking yellow, then red, with replacement abbreviated form). Now, I think I understand most of what we learn in class pretty well. I have an excellent teacher who takes the time to go through the material as thoroughly as possible given time constraints and is always open to questions. After my first few “bad” grades in the class, I started studying 1-3 hours before every test and quiz. I try to make it a point to double check my work if I have enough time (which I usually don’t).

So, I guess my question is, how do I avoid making stupid, silly mistakes like this in the future?

*And yes, I understand that most people would not consider having a 92 a bad grade, but the way I see it is, if I make grades like this right now, what’s going to happen to me in precal and calculus next year?

I think if you could figure this out you could write a book and make a zillion dollars.

Obviously double-checking is the best thing…maybe take your answer and work backwards to the original question to see if it is correct. Also make sure that the answer seems reasonable…like with your marble question if you get '1% you know that isn’t right.