I am just going into class 12 and want to prepare for jee as well as boards . But also I have a poor class 11 concepts what should I do

dear vinayak 
tahts the problem of every student , poor concept of class 11^th , dnt worry about that . 
frst of all make your 12^th strong so, that any ques of any difficulty level if asked u can answer that . 
and 2^nd thing at the wekends u can revise only the formula and reaction charts of class 11^th , 
just go through the askiitians revision notes and u will get short notes and imp points. 
and try making numericals of phy from prev year paper , 
but frst u have to concentrate on board then jee prep . 
ALL THE BEST 

REGARDS