WHILE PRE...START FROM WHICH SUB...?

It depends on your perception. Its is suggestable to start the difficult subjects first and then go for the rest.

I will go on the reverse. Therefore as rightly said by Mr.Chaitanya it is one's own comfort.

Start with theory subjects first and then go to the practical ones....

Yes, i also agree with Mr. Chaitanya that one should start with difficult subjects and as we finish those we get a lot of confidence which helps in completing the other subjects also quickly................but there is no method as such, u can do it the way u like