• Tense, Mood and Voice (Is what you're relating all in the past? In the present? Keep that point of view clear.)
• Person and Number (Are you talking about a single entity or a group?)
• Construction (If you are listing things, are they sentences? Are they just a series of nouns? Are all of your subheadings and titles the same construction?

A generic example of the tense issue is the following:

This major corporation did this and that major corporation did that before they go bankrupt a year ago. It comes as a big surprise to all of the shareholders that they didn't see this disaster brewing.

The tenses in the short example above are skewed between the past and present tenses (see below).

This major corporation did (past tense) this and that major corporation did (past tense) that before they go (present tense) bankrupt a year ago. It comes (present tense) as a big surprise to all of the shareholders that they didn't see (past tense) this disaster brewing.

To make this more consistent, it should read as follows:

This major corporation did (past tense) this and that major corporation did (past tense) that before they went (past tense) bankrupt a year ago. It came (past tense) as a big surprise to all of the shareholders that they didn't see (past tense) this disaster brewing.

Mood is one of those terribly tricky areas of grammar that we use regularly but of which we are often unaware. Most of what we say and write is in the indicative mood, but occasionally we venture into the mysterious realm of the subjunctive. Perhaps the most common mistake found is not using the subjunctive in a situation that is contrary to fact. The subjunctive is recognizable by using what appears to be the wrong verb with a subject. Normally in the indicative case we say -

In the subjunctive we use were throughout.

So when we make a statement that is contrary to fact (not the case), we should use the subjunctive. For example, it is incorrect to say -

If Bill Gates [he] was not so arrogant, we would have more sympathy for him.

It is incorrect because the phrase If Bill Gates was not so arrogant is contrary to fact; Bill Gates is arrogant. So we indicate that it is not true by using the subjunctive -

If Bill Gates [he] were not so arrogant, we would have more sympathy for him.

The question of voice is an important one and can make the difference between a strong positive presentation and a weak one. There are two voices - the active and the passive. In the active voice, the doer of the subsequent verb is the subject of a sentence or phrase. In the passive voice, the doer of the action is usually represented as the object of a preposition. For example -

The new organizational initiative will be led by Amelia. (passive)

Amelia will lead the new organizational initiative. (active)

These two examples basically say the same thing but the emphasis, focus and effect they create are different because of the voices they are stated in and the effect that has on us.

In the first example, the focus of the sentence is on the new organizational initiative which stands as a passive monolithic entity that somewhat coincidentally Amelia will lead. In the more straightforward active voice example, the doer Amelia directly performs the action and acts directly on the object of the verb. The effect on the reader/listener is obvious.

A common number error is to use plural verbs with singular nouns when the singular noun implies a group. For example, the sentence -

The Federation of International Banks were happy that the directors' meeting moved in their favor.

- has two errors of number in it. The error comes from the fact that while Federation of International Banks implies a group of banks, the actual word federation is a singular noun; the federation is a single entity. So not only should the verb be singular, but also the singular federation is not a they so the pronoun their is also incorrect. To make the sentence correct it should read -

The Federation of International Banks was happy that the summit meeting moved in its favor.

Along these same lines is the other common number error that involves the use of words like each, everyone and everybody. Although some say that the mistake is so widespread that it is becoming acceptable, those words describe singular entities. For example, the following sentence is incorrect.

Everyone in the room were convinced that their presentation was the best.

Again there are two errors. In this case, everyONE is a singular noun requiring a singular verb and singular modifying adjectives. The verb should be the singular was (a less common mistake) and the modifier of presentation should also be singular. An issue arises here as to which singular to use his, her, his/her, or his or her. Older traditional usage said that if there was at least one male in the group, then the his form should be used -

Everyone in the room was convinced that his presentation was the best.

This choice is now one of the least popular choices. Some people subscribe to the notion that women should be given equal and separate time and alternately use his and her in alternating paragraphs and examples. Perhaps the most common solution is the use of the combination forms his/her and his or her as demonstrated in the following examples:

Everyone in the room was convinced that his/her presentation was the best.

Everyone in the room was convinced that his or her presentation was the best.

Whatever the choice, their is not correct. Even though the implication is that there is a group of people involved, you are only talking about one of the group in these instances. Think about what the sentence actually says and not what it implies.

The key idea here is to keep your sentences consistent in how you construct them. This is commonly called parallel construction. A good example of this is in the construction of bulleted or numbered lists. For example -

The following plan best serves the election system:

• Nominating candidates,
• Stating candidates' ideas,
• Voting,
• The inauguration.

The previous bulleted list is inconsistent. The first three items begin with gerunds (verbal nouns- verbs that are made into nouns): nominating, hearing, and voting. The last item is presented in standard noun format. This list can be made consistent in a couple of ways - each bulleted item can be made into a noun, or else each bulleted item can be made into a gerund. For example -

- OR -

A final note while we're on the subject of bulleted lists -

Note that in the examples above, each item is separated with a comma because each item is only a short phrase. If each item were a whole sentence or clause, each would be separated and followed with a semicolon.