If your sole purpose is visiting hussian sagar for tourism you can get down at sanjeevayya park railway station (all secunderabad lingampalli mmts trains stop here)...
From sanjevayya park necklace road is 3km and the whole area is same you will see Greenery and water
If you are visiting for other purposes then sanjeevayya park station wont fit you
Instead you can break journey...
more... into two secunderabad to Begumpet and Begumpet to necklace road (only one station) ..but it's hard to find tickets for secunderabad to necklace road (ticket counter ppl refuse because there are no trains