Hi. The rules seem a little complicated. In general consonants tend to be attached to vowels (στρα-τός, ἐ-χθρός). To have a syllable starting from 2 or 3 consonants, there must be at least one Greek word starting from these 2 consonants (e.g. if there was not χθές, you could not separate ἐ-χθρός attaching all consonants to the last vowel, you should separate it as ἐχ-θρός. Because there is χθές, and other words starting from χθ, you can separate it as ἐ-χθρός).
When you have composite words you can divide them in their components, unless one of them is not intact. E.g. in the word Parakletos, you have two words, and they are both intact, therefore you separate as para-kletos (and if you need a break elsewhere, normally as pa-ra-kle-tos). In e.g. Παρέρχομαι, the word παρά is not intact, therefore you divide as πα-ρέρ-χο-μαι (notice also that I place ρ to the previous vowel in -ρερ-, because there is no Greek word starting with ρχ.