Personally, accuracy >> speed. People don't care how fast you can solve a problem if you can't solve it accurately. So, slow down a bit and focus on your points of errors. Maybe you're forgetting signs. Maybe the proper usage of the chain rule. Maybe you're copying a number down incorrectly. First focus on rectifying those errors. Once you start seeing that you're making less and less mistakes, focus on improving your pace. Start solving easier questions in a short amount of time, and then move onto harder ones.
This was my strategy too. I used to make a ton of stupid mistakes so I tried focusing on those errors first. And now, I've successfully minimized my errors and am able to do problems much faster.