Is this Human Behaviour? Your question is radically different to mine back in '08...mine was a Social Psych question about ingroup homogeneity.
Anyway, let's have a look at the question:
"critically evaluate the suggestion that from standard intellectual and cognitive assessments may not be accurate for some cultural groups, such as indigenous australians"
Firstly, critical analysis should not be a description of so and so said this, other so and so wrote this. Critical analysis needs to be critical. So when you do your literature search, look for reports which argue different standpoints. Often, when an article is published, other research articles will pop up in reply to the original article criticizing reliability or validity of the original study, keep a look out for this.
Also consider if an article has used previous research in a balanced manner and what sort of barrow they're trying to push (i.e. what are they trying to convince you?). And provide your opinion based on this conflicting research - what are you more swayed by and what do you view as more reliable and valid?
I haven't done cognitive psych since 2008 in first year (doing it next semester though) but I do remember that if you administer an intelligence test developed in one form of culture (e.g. Western) to another culture, they're highly likely to perform poorly due to the lack of experience in the first culture. If you have the Westen, Burton and Kowalski textbook, there's plenty of examples of this in Chapter 9.
To answer your questions: yes provide definitions. Note where theorists disagree on a certain definition. Include as much research (journal articles, studies, etc) as you can, but make sure this research is valid to answering your question. Don't just reference it because it mentions a term fleetingly. First year essays and reports usually require a minimum of 6 references in the marking criteria.
This is how I would attack this:
1. Read the appropriate textbook chapters. It's discouraged to reference the textbook, but they might let it slide in first year. Definitely not in the later years. Get ideas of different theories that apply to your question.
2. Look up references that are cited in the textbook to get info from the horses mouth, so to speak.
3. Conduct a literature review. Make sure all your articles are of an academic standard. Googling is merely not enough (though Google scholar has saved my life admittedly lol) because any one can set up a webpage on the net, and anyone can edit a wiki on the subject. Things that are peer reviewed = good.
4. Set up an essay structure plan. This will help to make things flow the way you want. Look at marking criteria and see how you can fulfil it.
5. WRITE WRITE WRITE. Be critical, stress a lot. It's the uni student way. Make sure your essay and references conforms to APA standards - this will get you easy marks!
6. Edit, review, make sure you have answered the question (I am guilty of not doing this!!)
7. Hand in, stress about something else. When you get the assignment back take the time to review what your marker has said.
Good luck, now I should stop babbling and do my work lol..