@EdRick - Here are some tricks I use with my students when we do our declarative and imperative sentences worksheets.
First, cross out any phrases or clauses that you can and still have a sentence that makes sense, like anything at the beginning of the sentence that has a comma after it, any prepositional phrases, etc.
Then, try added the clause "It is a fact that" to the beginning of the sentence. It will make sense with a declarative sentence, but with an imperative sentence, you'll be left with nonsense. "It is a fact that 'After dinner my mother suggested a walk in the park.'" Declarative sentence. "It is a fact that 'Before you come to the table, wash your hands please.'" You can reduce that to, "It is a fact that wash your hands please." Doesn't make sense, so it's an imperative sentence.