How can I score a 310+ in the Mains ?

Wow! You've set a very high bar for yourself, which is a good thing. A score over 310 would essentially rank you somewhere in the top 800 rank holders, which is a very conservative figure. You could do much better rank-wise if things go well. To score 310+ in JEE Mains, you will have to give up a lot of things. All distractions will have to be eliminated. You should be ready to work every second of every minute of every hour if you want to get such a high score. Some preparation tips have been illustrated in the link below. https://www.reviewadda.com/exam-jeemain-offline-tips