I did it via self study. I used the book mentioned at NTS website. usually i get low total in English and analytical. I was able to improve my analytical score via process of elimination. But i have a hard luck when i got good marks, there are no scholarship that i can apply, Not even local scholarship!
try to improve your logic in daily life. Like when i was sitting in exams hall i was deducing my opinion about the class. it will increase your speed of thinking and solving problems. More over i installed logical, IQ and maths games in my mobile i use to play them whenever i was getting bored or there is no electricity. Don't take too much pressure as i just started preparation just about a week before test date. try to increase your speed in quantitative section, extra time gives an edge in analytical.