Text summary is a useful exercice as it tests both your understanding and your vocabulary. Replacing phrase with precise nouns, adjectives or verbs is a big part of the job. That's why I would use 'correspondence' instead of 'writing to people'. Let's do a breakdown:
One of the most difficult aspects of corresponding with people you have not met face-to-face is establishing a personal relationship with them in order to show them that you are not just a letter-writing machine but a real person
One of the most difficult aspects: this says that there are several difficult aspects, and that this one is at the top of the list. We don't need to keep all these details in our final sentence: readers know that there's not only one difficult aspect, and the fact that it's at the top of the list is not vital. The fact that we talk about it already means it's important.
corresponding with people you have not met face-to-face: we can do away with that; the context will make it clear that we're talking about people who have not met.
establishing a personal relationship with them: That's the core of the sentence. I replaced that with "breaking the ice" to save some words.
in order to show them that you are not just a letter-writing machine but a real person: this is just a way of emphasizing "personal relationship". The person we correspond with certainly know we're not a machine (ask Turing). Consequently, we can discard this part.
Bottom line is, use precise vocabulary, don't hesitate to prune some secondary information, and rely on context to save words.
Now, say you still want to start with "Writing to people", as an extra constraint, I would say:
Writing to people you've not met comprises difficult aspects as making the relationship personal.
=> It's significantly longer, though closer to the original sentence. You be the judge.
FRC
