First select a good coaching institute online or offline ones
If you are aware of basics and few really required topics then it’s better to opt for online
But be sure to have modules and test series of any one institute along with NCERT and mtg fingertips for all subjects
Prepare from difficult topics ….once you gain confidence in these topics you will be more determined and confident while giving tests
Try to analyse your preparation at least weekly once or once in 15 days ….only preparing and not analysing won’t help
Try to positive throughout that you can do it ….try to have clean and ventilated study area and try to have some positive quotes around your study area
500+ won’t fetch you govt college so just try to score maximum marks you require to enter into best college