General Advice
Paper Mechanics
Strategies for Good Writing

Thesis
General Advice
Having a clear thesis
3 tests for a good thesis

Argument
Paragraph Structure
Topic Sentences
Strong Arguments
Checking your arguments
Before your final draft
Effective conclusions

Evidence
Handling Evidence
Quotation Format

Writing skills
Clarity
Grammatical Errors
The literary present
Sentence Fragments
The use of "I"
Word choice

Ask yourself the following questions:

1. Could you argue against your thesis. Put the word "not" in your thesis sentence, and consider arguing that thesis instead. If a reasonable person who read the same text(s) you did could argue against your thesis, then your own argument is worth defending. Otherwise, you may have a statement of fact.

2. Is the thesis worth arguing? Or is it too easy to prove? If there seems to be an abundance of evidence to support the thesis, it may not be worth arguing. (Again, a reasonable person probably wouldn't disagree with you.)

3. Are you explaining something? Consider that most theses should have two parts: an observation part, where you state that something is the case, and an explanation part, where you explain why that's the case, or explain the significance of that observation for the text. Most weak theses have only the observation part, without pursuing the larger questions.