Apart from civil engineering(1st preference), what should be my other 2 course preferences for JEE 2018?

All the branches are good in engineering. Choosing a branch totally depends on your interest. If we compare the branches then CSE and ECE is the most demanding branches among students and both have good scope in terms of job and growth. You should focus on getting top colleges rather focusing on branches. So, that you can get good placements. If you are interested in civil engineering go for it try to get admission in top colleges for Civil engineering. Good Luck!!