First of all,never go for quantity, always aim at quality!
Even if u study for 6 hrs but with pure devotion,its of gr8 use.
Try to study for 6-8 hrs a day.
Give 4-5 hrs to theory n the remaining tym to Numericals.
Always try to study chemistry in the morning so that the oxygen level increases in ur body n u'll be able to mug up more.
Focus on MECHANICS in Physics and on chemistry.
JEE 2011 will have higher proportions of the above 2 mentioned .
This yr Maths doesn't need any xtra practice.