Dont mind about AR10 early, you'll have a hard time to read AR7,8,9 aka the most used ARs. Especially 7 for your level.
If you really want to go for AR10, do it with HR. This will also get you used to the mod and improve your aim, acc and reading. Add HD and you have a nice mod combination for Insane diffs. BUT dont do that till youre really FCing Insanes (no 4 star ezpz Insanes, ~5 star Insanes with no miss and around 97% and higher)
Dont become one of those "ar10 1000 playcount cant read AR9 lol" guys. Theyre annoying and its like you skipped elementary and went straight into college.
Also, learn the difference between "reading" a map youve played hundreds of times and actually -reading- a map on the first try.
There are not too many that can actually read AR10, AR10,3 even less, but there are tons of idiots that claim that they can read it (on one map though, but that counts, doesnt it? NO it fucking doesnt)