some really good sketches there! tried a little, but lost/chucked all of the sketches as didnt think much to them...

have you tried some tutorials? they helped me loads.

these are good here

http://www.carbodydesign.com/car-des...torials.php#2d

do you have any "magic markers"?? looking by some of the toning on those you do, but if not, they are really good!

good luck!