Hey, 

About clearing the advance , it needs a lot of regularity, hardwork and time. Advance is an exam which is designed to seperate the best of mains. The first and the foremost step is to brush up basics so that they are on your fingertips.(During my JEE advanced, I prepared a rough notes of all the basic formulae and anything related to memorizing and it was handy for me to revise during the last moment)

As this is the peak time and you cannot go through the very minute concepts, practice as many previous year's papers as possible.( I practiced past 10 years papers which were published by Arihant along with the solutions)

Go through multiple mock tests so that you could introspect about where you stand enhance your preparation. This would surely improve your confidence. 

Also focus more on strong topics and forget those 10-20% syllabus you think you are not strong enough. Avoid procrastination.

Digging deeper, 

Study conic sections and circles since the questions asked are a little less twisted in this area. 

Visualisation is important when it comes to 3D geometry. The questions asled form this topic are a little complicated. 

Matrices and determinants are easy to slove. Most of the questions asked are direct. 

Trigonometry shouldnbe on finger tips. It is involved in many topics. Several angle and the values should be known orally. 

Binomial and other concepts are basic.  Learn the expansions and you're good to go. 

There are several tricks to solve the problems and they can be useful to solve a lengthy problem in no time. 

Study mechanics when it comes to physics as it is a really scoring part of the paper. Learn basic concepts from nuclear physics. Physics is simple and can be scoring if your basics are strong. 

Focus on nomenclature and train yourself in such a way that you should be able to identify the intermediary steps of the preparation proccesses. Study isomerism. Don't forget to study equivalency concept in physical chemistry. Go through NCERT text book for inorganic chemistry as most of the questions are asked directly. Try having the knowledge of the properties of all the elements. It is very helpful. Also you should know about the structures of compounds as potassium permanganate and potassium dichromate etc. And concentrate on the colour of the compounds. 

One of the most important habit is to optimistic and relaxed not only during the preparation but also in the examination center. Do not procrastinate. 

Thank you.