1. Agreement - Agreement in a sentence refers to all of the parts of the sentence corroborating with each other. For example, you wouldn't say "John have two pieces of toast and I has three." You would instead say, "John has two pieces of toast and I have three." The subjects and verbs need to be in agreement. Without sentence agreement you have all-out civil war in your sentence and no one knows what is going on. If your sentence parts don't agree with each other you will have to jump in and mediate, causing hard feelings all around.
2. Tense - Tense refers to time. What time is it in your sentence? Whatever time it is it should remain consistent throughout your whole piece of writing. If it was last week you are talking about, stay there. There are three tenses in writing, past tense, present tense and future tense. Here is an example of writing with mixed tenses: "Carrie wondered how she is going to finish in time, but Joe will help her." This sentence contains all three tenses, past in "wondered", present in "is" and future in "will". Pick a tense and stick to it! The sentence could read "Carry wonders how she will finish in time, but Joe will help."
3. Spelling - One of the most important things, and without it, you can kiss your credibility goodbye. Spell checkers are poor substitutes for knowing how to spell and can leave behind more errors than you realize. There are many different forms of words and your spell checker does not know which form you wanted to use. For example, "When Mark washed they're care, he forgot too putt on the wax."
4. Run-On Sentences - A run-on sentence is one that is just too darned long! Not only is it too long, it is incorrect. Usually, a run-on sentence can be made into two or more sentences with a little punctuation and style. An example of a run-on sentence might be: "We walked over to the commissary to get something to eat but it was closed so we didn't know what to do so we kept walking until we saw a restaurant and decided to go in and get something to eat but Andrew didn't want to eat there so we kept going for another mile." This sentence could have gone on for another mile too! Break up the sentence into smaller, more coherent parts.
5. Punctuation - It is very important to know your punctuation, even if you never plan on using a semicolon for the rest of your life. The most important thing to learn is where to put your commas, a common mistake among writers. Commas are used to separate parts of sentences that stand alone, such as those that are parenthetical. For example "There were too many flowers, not that I minded, but they took up most of the room." Avoid using commas after conjunctions like "but" and "and." Semi-colons and colons take up an entire chapter, read about them in your style book!
