Probably the most common question that upper belts hear from new BJJ practitioners is "What should I be working on?" The most obvious answer is, of course, the fundamentals, but the answer needs to go further than that. People who are new to Brazilian Jiu Jitsu also need to work on their mindset, specifically when things go bad. For your entire white belt career, you are more than likely going to be the nail instead of the hammer. You will be put in positions you have no idea how to get out of, and all of your strength and speed will seem pretty useless. The very first thing you have to learn is this: stay calm.
It sounds pretty easy, but try and think back to the first time you were mounted. You were probably taught mount escapes that day and began specific training for it. Your partner mounted you, and you did exactly what you learned in class. Trapped the arm, trapped the leg, and the next thing you know, you were getting arm barred or choked without realizing what happened. Then you tried to escape again, and then again, and each time you got more and more frustrated because the technique wasn't working. What happened next? You began pushing and trying to use you strength, which led to even faster submissions. We've all been there. That's how we all started.
As white belts, you will be in the worst positions for quite a bit. Take this opportunity to learn to control yourself. Go over a checklist in your mind. Am I breathing properly? Is my posture correct? What is my immediate escape option? What is my second escape option? Brazilian Jiu Jitsu is about escaping the worse possible situations and turning the tide of the battle. Think through you next move so it won't be your last. If you do end up getting tapped, ask your partner or an upper belt how you can correct your mistake. That's what they're there for.
Now is the time to lay the foundation for this type of mentality. If you watch upper belts roll, they look like they don't have a care in the world, even if they're in the worst possible situation. This is because they've been there countless times before and it is ingrained in their nature to remain calm and find the escape. Always look to find your calm like your predecessors. It is one of those things that you carry with you long after you step off the mats.