Before going anywhere, it is important to find out about the recommended and mandatory vaccinations in the destination country. In France, for example, poliomyelitis, diphtheria and tetanus vaccination is mandatory, and pertussis, tuberculosis (BCG) and MMR (measles, mumps and rubella) vaccination is recommended. You must therefore make sure you are up to date with these vaccinations.
More generally, vaccination against tick-borne encephalitis is highly recommended in Central Europe, Northern Europe and Eastern Europe, especially in spring and summer. For extended stays, it may also be wise to receive rabies vaccination, especially in Eastern Europe. It is in no way mandatory, however.
Lastly, vaccination against typhoid fever and hepatitis A is recommended for extended stays, or in countries with precarious conditions such as Moldova, Romania, southern Russia, Ukraine and Belarus.