Your SA rating will suffer if you play short races and those races feature crashes or offs.
The best thing I can suggest to increase SA, gain track knowledge and learn racing line is to do at least one 30 minute quick race on every track in the game with 24 other cars on the grid.
Start mid pack and get used to rolling starts (they're slightly different online so may be worth looking for an online tutorial to know what to expect)
Experiment with the AI difficulty for this. I worked off making them fast but not too fast. Between 80-90 should work but dial it back if you're struggling to keep up. Turn aggressiveness down to around 60 so you don't get into any bother.
The point of this isn't to go fast. It's just to practice and will help with a few things so stay in line and maintain your position.
You will gain a few things from this. SA will increase every lap you do. If you aren't pushing then you shouldn't be risking collisions so clean laps are very doable. If the AI is tough to keep up with then dial them back.
Drive round for a 30 minute stint on every track to learn the tracks, get used to driving close to other cars and using your radar. (Crew chief will massively help you with this too)
Once you have done 4 clean laps in a row you will gain all 3 track stars.
This may sound boring but will give you 30 minutes of experience on each track, show you a reasonable racing line and get you used to driving in a train. I'd suggest doing that before going online as it will boost your SA to the point where you can access safer servers.
It's a good way to practice and build SA/track knowledge but it won't prepare you for being sideswiped by a spinning car on Monza T1.
It's definitely a cheap way to build your SA but once you have done this type of practice race on every track your SA should be at least 70. The key is being within 1 second gap to the next car in front or behind. Driving around an empty track to practice doesn't increase your SA so you really need the other cars about to help build it. It's about racing close and safe. Hope that helps.