My advice is it depends where you are flying.
If you are flying through EU- just go straight into it. There are usually 2 controllers working one sector- one executive and one planner.
If you are flying through a second tier airspace eg- China, russia, Middle east, indonesia or a third tier' provider eg- australia, Moresby, give the controller a warning if it something complicated. The reason is this- they are on their own- eg they have to co-ordinate everything while listening to the frequency, or, the English become a problem when it something non standard.
have fun