This isn't just for the SAT, but I am a very nervous person and cannot handle big situations. The next test is my last chance to score well, and my last 2 real SAT's were 150-200 points below my practice test scores.
I feel like my mind cannot focus and I get butterflies inside. I think the nervous energy leads to careless errors. Yes, I know this is just a test that I'll probably never remember, but it is too significant now as a student. How can I overcome my nerves to get the same scores I get on the practice tests?
I'd recommend that you try some mindfulness techniques when you find yourself getting stressed during the test. Think of a calming phrase. In moments of panic, focus on your breathing and repeat this phrase in your mind. It can just be something simple like "breathe in, breathe out, move on." Do this for 5-10 seconds to clear your mind. Even just breathing deeply for a few seconds can help.
Another variation on this technique is choosing a number and subtracting another odd number from it repeatedly so that your anxious thoughts get pushed to the back of your mind (for example, start at 250, keep subtracting 7 over and over until your mind is clear).
I'd also recommend that you go to bed early the night before the test. Don't stay up studying until the last minute. You should consider doing some physical exercise sometime in the 24 hour period before the test as well - it's a natural anxiety reducer!