IMO the best cars to start with would be the UF1 XFG or XRG, preferably the XRG. They are slow, not just with acceleration but the car in general is just slow with reacting or acting on things and would give you a good start into really learning to play LFS.
If you have to drive single seaters I would start off in the FOX or MRT-5, probably the MRT, learn a couple tracks within a second or so of WR then start thinking about moving into the F08 and more tracks.
When I started LFS I put in over 1500 laps in the MRT at FE club to get the basics down and by then I was running within a second of WR. I didn't spend all my time at that track, but learning one track/car very well will give you an idea on how to drive the next config and how hard the car can be pushed.
I had a good 7-8k miles in the game by the time I had put 1500 laps into FE club too. Take your time, have patience and most of all practice! I think I am at a good 4-5k laps now at FE club in all the cars=/ Goodluck =)