reposting one of my comments as it may be useful too all (also i typed so much , wanted it to benifit others too )
Firstly go through the basic NCERT's for economics and history , for economics go for 11th &12th. ,macro and micro And for history , go through (quickly) 6-12th , specific chapeter wise reading is suggested by mrunal on his site (mrunal.org), u can ignore science , if you have been a science studentConfusion Regarding old and New ncertUse new NCERT's , no doubt the older NCERT's are better and more detailed , Upsc has time and again asked from the topics specifically in old NCERTs , but now the pattern has chanhed , a lot of emphasis is on level playing feild , so that a guy preparing in Delhi , and someone preparing is far tribal areas must have equal opportunity 2.
Supplement your basic preprations done via ncerts with spectrum modern History
(a standard book, i.e S.B) 3.
go through Laxmikant Indian polity throughly ( u need ti go through it 4-5 times during your prep) (S.B)
Read laxmikant systematically as explained by mrunal , and suppliment with class lectures or youtube lectures by FantasicFundas
Go through Hindu or Indian Express daily , a lot has been talked about how to read newspapers effectively ,Google it5.
Balyan's art & culture + sriram economy must be done too6.
Focous and finish your optional ASAP , and go throigh IOI(insights on India) booklist for the same7.
read /follow IOI / iasbaba or vision's monthly Current affairs8.
Dont ignore CSAT , be done with it in first month itself
Few books like DD basu plassy to partition, 2-3 more are also suggested as basic books but u dont need then , not for prelims atleast
Finally dont make it a huwaaa ,that UPSC is tough , it isnt , its the competition thats tough , the paper isnt , most fail as they get scared if exam and psychologically belive that its too much to prepare and hence leve critical topics , points while preparing which results in throwing them out of the competitiuon