Personally I find racing offline with ai good practice for racing online with others. Trick is to race with the ai and not attempt to blow past them all at once. If you attack one car at a time you'll soon find where the safe zones are and it prepares you for all the odd brake points and drivers cutting in on you. Something that you find all to often online. Imho if you can race clean with LFS's AI your ready for most that online racing can present.
Another cause of "bad" driving is a direct result of hot-lapping, ppl get so set in specific lines they forget how to run in a crowd. You see this alot on lap 1 turn 1, personally, without ever looking, I always assume someone is beside me and I adjust my line accordingly, but, even doing that you still find someone not thinking and fires off to the preferred line, which isn't really the correct line in traffic.
But the grandaddy of all is the chaps that cause the big wrecks, then proceed to request a restart, over and over and over and over. You soon see pll blocking the chat, Thank god....well atteast the devs for including this function
In a 5-6 lap race, this attitude, I wrecked, please forgive me, I want another try.....NOW!! is hogwash. Suck it up, lick your wounds and run some much needed practice laps.