You can write an effective sentence simply by using different sentence patterns to add style and variety.
(1) Putting two simple sentences together (i.e. a compound sentence pattern) by using a semicolon, instead of a conjunction (and, but, or, nor, for, so, yet):
e.g. I was thirsty; I drank 3 glasses of water. (Here, a semicolon is used to replace a conjunction, such as "and" or "so.")
Please note: Without the semicolon, the sentence becomes a run-on sentence, and is therefore grammatically INCORRECT.
e.g. I was thirsty I drank 3 glasses of water. (INCORRECT: a run-on sentence with two INDEPENDENT sentences joined together without a conjunction).
Please also note: Adding a comma, however, does not make the sentence CORRECT.
e.g. I was thirsty, I drank 3 glasses of water. (Here, the sentence has a comma slice, and therefore is INCORRECT.)
Another common mistake in joining sentences is a sentence fragment:
e.g. The reason for my drinking 3 glasses of water being extremely thirsty. (The sentence is INCORRECT because "being" is the wrong verb form here.)
However, a colon can be used in place of a semicolon:
e.g. I was extremely thirsty: I drank 3 glasses of water. (Here, the sentence is CORRECT, but the meaning is slightly different. When a colon is used, what follows the colon explains what precedes the colon; in other words, it explains "how thirsty" rather than "the result" of being thirsty.
To illustrate, compare the following:
I was tired; I went to bed immediately (going to bed as a result of being tired).
I was extremely tired: I went to bed immediately (explaining how tired I was).
(2) The compound sentence pattern can have variation by adding adverb connectors (accordingly, consequently, hence, moreover, therefore, thus) :
e.g. I was tired; therefore, I went to bed immediately.
(3) The compound sentence pattern can further be expanded by the use of coordinating conjunctions (and, but, for, or, nor, for, so, yet).
e.g. I was tired; I went to bed immediately, and I slept until dawn.
e.g. I was tired; I went to bed immediately, but I could not sleep.
e.g. I was tired; I went to bed immediately: I could not sleep.