Transitional words

• "However" is a transitional word that moves your ideas from one sentence to another. It's very similar to "but." It's used to show contrasts and differences.

Ex: Having a car can be very convenient; however, it's expensive to buy and maintain one.

• "Therefore" is very similar to "as a result." Something is a fact, and after thinking about this fact, you can make a conclusion. It sounds a little formal in everyday speech but not uncommon. It's very frequently used when writing.

Ex:His skin burns very easily; therefore, he's decided to stay under an umbrella and wear lots of sunscreen.

• "Consequently" is very similar to "so" and "therefore." Like "therefore" it's a conjunctive adverb (the term is not important!). It usually appears in the middle of sentence, but it may also be used at the beginning of sentence. If you know what the word "consequence" means, you shouldn't have any trouble with this.

Ex:Hector decided not to use a map; consequently, he got lost and never found his way out of the forest. There he died.

• 
  "Because" and "because of" are used to give reasons or to indicate the source of a situation. They answer questions asked with the word "why."
  "Because" is used with clauses. "Because of" is used with phrases and, sometimes, single words.

Ex:
*He's starting to get nervous because he has so much work to do and not enough time to finish it all. (A subject and a verb come after "because.")
*He's feeling a lot of stress because of his job.
(A prepositional phrase comes after "because of.")

• "Due to" is very similar to "because of." It gives a reason for why something is true. You can use "due to" with phrases and single words, but you can't use "due to" with a clause.

Ex:
*Traffic was very slow coming home today due to a heavy snowstorm.
(notice that after "due to" you can't use a verb. )
*Due to a broken wing, this bird can't fly.
(This sentence begins with "due to" and is followed by a noun and a comma. It explains why the bird can't fly.)