Like many other people, I didn't practice for AWA until the very last minute. Only a week before my exam, I started reading the template chineseburned posted and after that, I wrote one essay everyday during my lunch hour at work. At night, I would come home and discuss the argument with my husband to see what the flaws were.
Having written only 6-7 essays, I ended up scoring 6.0 on the actual exam. It was a huge surprise for me because I knew my essay was by no means perfect from a grammatical or language point of view. However, I do believe that the most important part of your essay is the flaws you find. If you present a thorough analysis of the argument, you can still score a 6.0 even if you have some grammatical mistakes or if you don't have great choice of words.
I highly recommend
Magoosh and Grockit for the types of flaws on the GMAT AWA (since I wasn't allowed to post the links, I'm copying the text for you):
1- Grockit
The given paragraphs on the AWA Argument essay will always exhibit some flaws in reasoning; while the types of flaws are potentially limitless, most of them will fall into one of these categories.
- Assuming that characteristics of a group apply to each member of that group
- Assuming that a certain condition is necessary for a certain outcome
- Drawing a weak analogy between two things
- Confusing a cause-effect relationship with a correlation (famously known as post hoc ergo propter hoc, i.e. correlation does not imply causation)
- Relying on inappropriate or potentially unrepresentative statistics
- Relying on biased or tainted data (methods for collecting data must be unbiased and the poll responses must be credible)
2-
Magoosh 1) Vague words
2) Inappropriate Comparisons
3) Errors in Causality
4) Basic Economics
5) Sampling Problems
6) Overconfident Conclusions
Hope you find this information helpful.
Best of luck,