Which manuals should I study before flying to France, Portugal and Switzerland?
For common procedures and or VFR rules you want to check the respective countries' AIP:


Switzerland   http://www.skyguide.ch/en/services/aim-services/
the other countries you mentioned can be found from this link collection http://www.eddh.de/equipment/ais.html

you may want to check the website of Eurocontrol here you can find IFR standard arrivals and departures


No warranty! Please prepare your flight carefully.