According to me, it all depends on what is the purpose of the map: Is it representing the layout on which a game will take place (in that case, you can define climate areas with different perks and disavantages like with the Total War's map), but if it's for your own world, I think it would be better for you to use real climate maps and try to see distribution patterns (mediterranean climate around the basin, etc.). That way, you could build your world in a believable way.
I suggest you take a look on phytogeographic maps, they usually give you a nice overview of what kind of flora you'd expect on a given area (it also reflects the temperature and climate). After building your areas, you then can focus on the actual vegetation you want to put inside and how you want to represent it.
That would be the way I would create a map of a world because vegetation is possibly one of the most characteristic feature to distinguish climate areas (along with geology, hydrology, etc.).
Here are some maps you probably can take a look at to see how you can build you areas.
world-natural-vegetation-map.jpg
Floristic_regions_in_Europe_(english).png
phytogeo.JPG