Ashould follow a dependent clause when the dependent clause comes first in a sentence.

colon
comma
period
semicolon

Hello.

A comma should follow a dependent clause when the dependent clause comes first in a sentence.

A dependent clause is a clause that depends on the independent one and to have meaning because it does not make sense by itself. Examples:

Because she was sleeping; since the boys were playing

As they do not convey complete meaning by themselves, they are dependent clauses.

Therefore, to complete the meaning, we put a comma before the independent clause and after the dependent clause to convey its meaning. Examples:  Since the boys were lated, they missed their bus.

On the other hand, when an independent clause appears first in the sentence we don't put a comma between independent and dependent clauses. For example:  She didn't speak because she was eating.

A period would cut the two ideas and they have a very close semantic relationship. A colon and semicolon would not apply in this case because it is not one of the rules of their usage.

Hope this helps.