Do I apply adhesive to the tile or floor?

[batiling]

I use 20mm round notch trowel for all my floors,apply to floor where i can and also covers any imperfections on existing floor.

 

[SanojW]

You said you have a solid ply subfloor.
It would be important to comment that you might have issues if you tile directly on plywood. Best is to use a membrane inbetween. Reason is that plywood will extend and contract with temperature and moisture changes, while tiles and glue are very more stable, and can cause the tiles to release.
I would recommend using a stable substrate between the ply and the tiles - check hardware store for recommendations, there are many different solutions.