The guttural letters are the following: video
א ה ח ע ר
Gutturals will never accept a dagesh, and they do not like vocal shevas.
In light of the former, study compensatory lengthening.
In light of the latter, know that a sheva under a guttural will become a composite sheva.
The gutturals affect the conjugation of verbs by “weakening” the root of the word. cf. weak verb.
gutturals prefer A-Type vowels.