Hi Dave
I'm going to be honest here: You will meet people who get on your back over nothing, and take the game too seriously. It's only happened to me about three times since I started playing, so don't get worried about that. It's just something that happens occasionally and if it happens on a crowded server, the guy who's berating you for no reason usually gets called out by the rest of the server. People will stand up for anyone who's been wronged, but I feel that not telling you about the few individuals who make this game less fun wouldn't be fair.
The vast majority of people who play this game are great, very friendly and understanding towards people who are new to it. The problem is that in racing games, much more so than in other genres, people get very caught up in the moment and get riled up easily. It's why they're extremely wary of newcomers. Opinions are formed before you even prove yourself, and a lot of players seem to equate fast lap times with good driving when it's often quite the opposite. The best racing I've had is with drivers in the midfield or towards the back, because they concentrate more on being fair towards others and avoiding contact. This is the key to gaining confidence online. As long as you can hold one line and let other drivers know where you intend to go, they will do the same for you and before you know it, you'll stop worrying about getting in others' way.
I can see how it's intimidating for new racers. The most popular servers greet you with something like "Welcome to our server, if you do any of the following things you will be banned". Frankly, seeing the word 'banned' appear the first time I join a server is enough to make me doubt my own abilities and think that I'll inadvertently get myself kicked out. It's like the general attitude is that if a new guy makes any kind of mistake, he's going to be one of those people who gets in everyone's way. Definitely not the case, but try telling that to everyone on a server.
I think what I'm trying to say is that, even though online racing in LFS is very daunting at first, if you can just prove yourself as a clean and fair driver it doesn't matter how fast you are. It might take a bit of practice in single player, but that's worth it. I'd second the idea of choosing a car like the XFG to start with, and just learning about it. I also think joining a server and introducing yourself helps immediately. People will be more than willing to help you get going online, as well as on the forums. For what it's worth, just making this thread says to me that you're thinking more about others than yourself, and that you're already much more polite than half the people I race against. As far as I can see, you've no reason to doubt yourself.