How the power plant overall efficiency can improve?

To improve Your Power plant Efficiency,you need to First Analyze which type of Power plant you have.

If your plant is using Gas engines or any types of Engines you can Use Heat Recovery Steam Generator to utilize waste heat and Convert it to Electricity .

efficiency =Heat Output /Heat Input .

Either We have reduced Heat Input by regenerative cycle by selecting optimum feed water temperature

Heat output by reheat cycle increasing power output of Turbine .

Any Power plant 60 -65% removal of Latent heat of exhaust (Condenser)  we have try  to utilize maximum energy from STG  (Bleed steam for Heaters ,Process steam if required ).

The above is simple explanation