Salary income is out of the purview of GST by virtue of Para 1 of SCHEDULE III of the CGST Act 2017. Hence no GST on Salary income.
As far as Rental income is concerned, Rent received from a "Commercial Property" is leviable to GST. Residential Property let out for Residential purpose is EXEMPTED by Notification No. 12/2017, CT ( RATE ) dated 28.06.2017.
Since your Aggregate Turnover does not exceed the threshold limit of Rs.20 lakhs, you are not required to take Registration under GST.