I myself have fairly strong visualization skills, however I still struggle to draw poses straight from my mind - I tend to have problems with anatomy and perspective. When posing a character for design I do something simple - head on, or 3/4 angle, usually hands up holding something to get a better view of the torso and for some interest. Else, I like to have the character doing something that reveals a part of their story or personality. Maybe a small scene of them working if their job is interesting, or if they have any neat hobbies. An action pose if they're always running around, or showing how they like to chill out or hang out with friends, or interacting with something from their story or universe.
Reference photos are my friend - my favourite is definitely senshistock - the gallery is very well organized and there's a large variety of poses, so if I know what kind of pose I want my character to be in (sitting, standing, jumping, etc) I can usually find a reference pretty quickly. I think this is could still be useful for you if you can't visualize how you want your character to pose - maybe you can browse until you find some you like?
Another thing I've recently discovered that I haven't had the chance to use but that seems quite helpful are 3D pose apps. I have 2 for my phone called 'Make A Pose' and 'MagicPoses' (I'm sure there will be ones for the computer as well) - they let you manipulate and pose a 3d model of a person, and get any view of it. Since it's virtual 3d space the perspective won't be perfectly realistic, and the body types are usually limited, but they still seem quite helpful and I'm excited to try them out more.
I hope any of this helps!