Definitely give it a go mate...I am new to online as well...its a whole new ball game. I have been having a fly on the ATAG server most nights the past week or so...still haven't gotten a kill but have been able to score a few hits on opponents here and there. One day, one day.
I have also had the pleasure of being shot down by some names I've seen on these boards, MX.MR X and Mogas to name a few.
The thing I am really enjoying is that I know what mistakes I am making as I am making them...and online, such mistakes really make a difference. When I was able to actually score a few hits, it was also due to my not making a mistake (up until that point at least, the tables turned pretty quickly thereafter LOL)
Anyway, for whats its worth, just jump in and give it a go. You'll figure things out as you go.