"Think of" usually means "bring to mind". "I just thought of something!" (Something just popped into my mind.) "I'm thinking of the time when we went to the beach." (I'm bringing it to mind.) "Think about" means to go over it in your mind. "I'm thinking about going to the movies tomorrow." (I'm going over in my mind whether or not I should.) "I'm thinking about the time when we went to the beach." (I'm going through the memory.) As we can see from my examples, sometimes they are exchangeable. "Especial" is wrong, it's only ever "special". In terms of the adverb, "especially" is used to mean "very" or "extremely", or "particularly". Both "especially" and "specially" can mean "for a special purpose", and only "specially" means "in a special manner". "That food was especially good." (Very/extremely) "I like all of them, but especially him." (Particularly) "It was made especially/specially for her." (For a special purpose) "She was treated specially on her birthday." (In a special manner)

Can you think of anyone who would like to study with you? Think of a number between 1 and 10. I loved my late mum - I think about her every day. You need to think about your work commitments before choosing holiday dates. Think of and think about are sometimes interchangeable, depending on the meaning. "of" suggests a shorter time and something more specific. "about" suggests a longer time and something less specific.

Think of something means you're at least aware of the thing. If you think about something more focussed or more attention attention.