Is there any strategy in trading f&o where I can get an assured (or partially assured) rate of return? Something like low risk with good returns

Assured return : Not possible.

Low risk and good return - try

debit option spread.

long strangle/straddle ahead of anticipated move.

all the best.

creat your own trading system and try Low risk and good returns

like this

https://drive.google.com/open?id=1Afg_3k3396GL5D6HGKzgyGU1egvkpUnnyTde7TRh07w&authuser=0

There is no thing like assured return in stock market. Change your approach to “Low Risk high rewards” Probabilities that can give consistent gains on long run.