Though there are some nuances I am omitting here, picking out a dependent clause is about finding the subject and verb and then checking for a word out in the front that goes with that subject and verb.
The thing that makes this a bit easier is that there are really a limited number of words that start dependent clauses:
relative pronouns: who, whom, whose, which, that
subordinate conjunctions: after, before, until, unless, if, as, as if, as though, when, where, whether, because, since (and some others)
Here are some samples of dependent clauses:
...that he is here...
...when we arrived at the house...
...because there were so few left...
...who is coming here tonight...
...though I am not sure of the date...
There is much to learn about these clauses. I will be giving a four-hour seminar later this year on how to find clauses and what to do with them once you find them.
Happy punctuating.
Margie