How to fix 50% of your grammar problems
According to The Writing Center <uark.edu/write> and Sean Chapman

1. Learn what makes a sentence—a sentence is a group of words containing, at the very least, a noun and a verb. (Read some William Faulkner to see a sentence at its very most). So, a sentence is this: John ran. Here is another sentence: John fell. Now we have to combine these two sentences.

2. Here are four major ways to combine two sentences correctly and one way to combine verbs:

a.) John ran, and John fell.

 

 

Combine with a coordinating conjunction—always use a comma before the conjunction. Use the acronym FANBOYS to help you remember these coordinating conjunctions: for, and, nor, but, or, yet, so.

b.) John ran; however, John fell.

 

 

Combine with a conjunctive adverb; this sounds complex, but it just means use the words "however," "thus," or "therefore." These words take a semicolon before them and a comma after them. Think of this as starting a new sentence with the word however.

c.) John ran; John fell.

 

Use a semicolon instead of a period. In most cases a semicolon is just that, a sort of “junior” period you use when you want to imply a connection between two sentences.
d.) John ran. John fell. Simply write two sentences with a period.

e.) John ran and fell.

 

 

Change the two sentences subtly by combining verbs instead of the whole sentences. Note that you do not use a comma before the coordinating conjunction when joining verbs.

 

3. If you begin a sentence with an introductory clause, you need a comma. See the clever example I just wrote. Notice that I began the sentence with "if." Other words to look out for: When, After, Before, While, Since, Once, Whenever (note these have to do with time) and Because, Although, Though, As if, While Wherever, Unless. That’s what you should do, but why? The easiest way to think of it for me, is that you need to tell the reader that the subject of the sentence, the focus of the thought, is coming up. In the first sentence of this paragraph, "you" is the subject, the most important element, and I need to tell the reader, “perk up, here comes the subject.”

4. The word "affect" is a verb; the word "effect" is a noun. Think of this: “The effects of the test will affect thousands.” I always pair effect with the to remind me: The effect. I just remember those e’s next to each other. Beware that this rule usually works; there are a few exceptions.

5. Check the spelling of these words: cannot, all right, a lot, too, their, and its.