Hi,
Have you taken the powerprep tests? Take them as many times as you can, I took the powerprep,each of the two test almost 6-7 times,U get the same format as the powerprep and if you have taken powerprep at home then you feel relaxed and its easy for you to answer,trust me it helps a lot.
Also go through all the pages of the essays and grammar given on this website that helps a lot.
Read the essays ppl have posted, you get a good idea abt what to write abt,I had handwritten the essay and in US they allow you to handwrite if you want.
The grammar in the final test is easy but b careful while reading the sentence,because they have at times mistake which is very subtle,again if you have done powerprep it helps to find the mistake,u know what you shd look for in the final test.
Finally b cool and relaxed,
And yes one more thing from my experience I can say that the final score you get is +/-- 10-20 of the powerprep score
I hope this helps,
Best of luck,
And last but not the list pray to HIM,he helps !
Regards,