How do I add a simple amp stage to existing RF module

I planning to use a tranceiver module like this one http://www.radio-modules.com/product...-modules.shtml or similar but need to boost power a bit to get 4000m range in open air. I guess I would need app. 500mW to make this happen.

Have no experience in how to do this and would like to see some example designs solving this issue. How do I add flow direction controll? i.e. Do I need an antenna switch?

Use a high gain antenna ( yagi ). more elements the better. if you double you power of the transmitter the receiver will only show 3 more on the s meter.
a good antenna makes all the differents.

if he employ the 2 concepts he will geain alot , good antenna and increase the TX power

there alot of of the shelf amp modules in the market , u just need to select one , with the output power u need and with good gain

khouly