Sentence Fragments
These are incomplete sentences. Remember that ALL SENTENCES need a subject and a verb.
Example: She was an interesting talker. (This is a complete sentence.) A woman who had traveled all over the world and lived in 7 countries. (This is a fragment.)

Comma Errors
Periods and commas go inside quotation marks.
Example: I am consistently amazed by the TV show "The X-Files."
There are no exceptions to this rule. Question marks and exclamation points and colons go outside quotation marks.

Two sentences cannot be separated by a comma. That’s called a run-on sentence.
Example: I went to the store, I bought milk.
This is WRONG. Your options are:
I went to the store. I bought milk.
I went to the store; I bought milk.
I went to the store, and I bought milk.

Agreement Errors A subject must agree with or match the verb. This means if you have a single subject, you need a single verb.
Examples:
The Jerry Springer show is strange.
Many talk shows are strange.

But, while these examples are simple, some subject/verb agreements are not so easy to spot.
She is one of those people who are never ready on time. (correct)
She is one of those people who is never ready on time. (incorrect)

She is one of those people who are never ready on time.

In this case, the subject of the sentence is the word people instead of she.

Organizational Tips:

Methods Of Organizing Your Paper
First, narrow down your topic into something manageable. Too often, students want to write about subjects that entire books have covered. Writing about High Definition Television is just too broad. Writing about the economic issues surrounding the adoption of High Definition Television will work. Next, organizing your paper will help you determine how to write it.

Organizing before you write gives your ideas a structure to cling to; it allows you to articulate, analyze, and clarify your thoughts. If you devise some structure for your paper before you begin to search for supporting evidence, it’ll save lots of time in the research process.
Organization involves two components:

1- determining a method of organization for the paper, and
2- drawing up an outline which applies your ideas to that method.

Determining organization method
Here are a few strategies you can use to develop papers:

Chronological order:
Paragraphs separate the process or series of events into major stages.

Classification:
Paragraphs divide the material into major categories and distinguish between them.

Increasing importance:
Paragraphs are arranged so that the most important point comes last, thus building the paper's strength.

Cause and effect
Indicates causal relationships between things and events.

Comparison and contrast
Similarities and differences
Although one pattern should serve as the overall organizing framework, your argument can use a combination of these strategies within paragraphs.

The First Draft

The first draft of your paper is the place where you can write anything and everything down and determine whether or not it works. Although you have prepared an outline of your basic points, it is likely that the process of composing an initial draft will alter your original plans somewhat. The composition of any paper is a journey through the tangled underbrush of your unformed ideas, and hacking from one end to the other will clear a path to a more definite perspective on your material, eliminating the weak points that you cannot prove and the flaws that undermine your argument. Your messy first draft will help you clarify the issues.
Just get it down. Revise later.

It is important to realize that writing is a way of thinking. Do not feel that you have to have all of your thoughts fully organized in your head before putting fingers to keyboard.
Once you have done your research and planned your outline, the best way to think about your paper is to write it. There is no need to feel disappointed with a messy, even incoherent first draft. The purpose of the initial draft is to produce raw material, not to dazzle the critics with your finely-shaped prose. Having something on paper gives you something to work with.

Revising

Now that you have a mass of print before you, your task is to lick it into something resembling an paper. Your principal concerns are: clarity, coherence and unity.

Clarity
This means getting rid of wordiness.
Vary your sentence structure – for example, don’t begin three sentences in a row with The. Watch for passive sentences ("A decision was made by the Premier to resign") and, unless the passive voice is crucial, change them to active ones ("The Premier decided to resign").

Coherence.
One thought follows another. Every sentence, every paragraph is neatly flowing
It doesn’t matter how strong your ideas are if they are not expressed coherently.

Unity
Check everything you have written to make sure that it

List the areas you are going to cover, ensuring it addresses the purpose of the paper.

Sketch out the proposal, and discuss with your tutor, take on board your tutors comments.

Research !

Make sure you reference as you go and compile your bibliography, essential.

Get writing and good luck !