I've popped another PhD cherry and received my first invitation to review a journal article :) I've no idea how this happened as I didn't apply to do it or anything!

I'm just wondering does anyone have any experience of this and can offer any words of wisdom? I'm so worried I'll read the article and just have nothing to say about it!

Consider:
1) Will the paper be of interest to the reader?
2) Is it likely (after any amendment) if the paper will be publishable?

Remember:
- They cannot change the methodology- the authors can only provide clarification or acknowledge limitations.
- Your role is not to be a copywriter- if spelling and grammar need amending, make a general statement about recommending proof-reading. Don't cite every example.

Make your response structured!

It's worth having a chat with your supervisor about what disciplinary norms are for your subject e.g. on length of review, and to get a sense of how the particular journal is viewed in the field quality-wise. You might for instance be minded to recommend accept for a graduate journal that you know struggles for submissions, when you'd recommend reject for the same article at a top-ranked journal.
Don't reject something because the article doesn't use your preferred theory or method - try to be open-minded however committed you feel to your own research choices.
I saw this on twitter and thought it worth posting as even if nowhere near your subject might be helpful for someone doing a search in future:

Agree with the above comments. The field/discipline is very important, as how this is done will differ greatly across disciplines.

Another thing to note is focusing on the point of the article as that will also help direct your focus, or the type of article it is.

I.e. is this a more theoretical piece? In which case you would want to pay particular attention to the interpretation of theory and how it's being utilised. Is this a presentation of results and findings? Then acute focus would be on methodology, data analysis and discussion. Have they provided a sufficient survey of the field in their literature review? Are there key people they've excluded, or literature you feel could benefit the paper?

Does the article actually achieve what it's trying to set out to do? Are they referencing original sources or constantly relying on interpretations? Do you think the discussion of the results is good or misinformed? Is the 'so what' present in the piece?

The best and most helpful reviews I've had on my own stuff (qualitative sociology/cultural studies) have been those who take a structured approach, so go section by section (i.e. argument, theory, method, etc).