Whenever you come home from a class, be sure to practice what you remember when you get home. For this, spend no more than 5-10 minutes a day to help remember the details you were taught.
Since you mentioned "sport" taekwondo, I suggest you spend time at home also developing your flexibility. Walking, jogging, biking, jump rope - those are great activities to help get the blood going. After a few minutes of aerobic activity, practice your kicks or your forms.
From time to time, you may go through training plateaus. You'll either become bored, or feel things are too repetitive, or that you're not learning anything. This is normal, don't fight it. Take a few weeks off, and in that time, do some research on your style, or your instructor, or other styles. Change up your warm-up routines. Or read up on Korean culture - pop culture, traditional culture, customs, music, language. Then go back to class.
Most important is to listen to your instructor. Remember that there is no best style. If you trust your instructor, then train hard, and be serious about what you're doing.
In your comments about WTF and self-defense... Yes, you are right. Your style of taekwondo is called "Kukkiwon", and is the style used in the Olympics. WTF is the organization which manages competition and is the conduit for the Olympics. It is heavily sport-oriented, and typically, self-defense is not taught in most schools. The majority of self-defense which is taught is not taught well enough, and the students don't get a lot of practice with it. It is a rare school indeed which teaches good self-defense in the WTF/Kukkiwon system. That does not in any way mean the school is no good. Just know that Kukkiwon does not expect its students to have good self-defense skills: it's not part of their curriculum. They're into competition, not self-defense. As long as you know that going in, nothing to worry about.
That also doesn't mean the style is not good for self-defense (it very much is), but if you are not taught the principles of good self-defense, then what you are learning in your school will not help much. As you test, your instructor will focus on certain things, like forms, breaking, techniques, sparring, etc. But if self-defense is not practiced regularly, then, the quality of skills here won't help you much.
Having said that, let it rest. If you really want self-defense, talk to your instructor and see what is provided. If you don't care, then this is an area of taekwondo politics you don't want to get involved with. It is always the case that from someone else's perspective, taekwondo is horrible, or MMA is horrible, or muay thai is horrible, or boxing... yada-yada-yada.
Just train. Stay out of the politics, it will ruin your training if you listen to the yahoos out there. No best style, no worst style. Just good (or bad) instructors, and good (or bad) students.