I (unfortunately [but not really because I got what I deserved]) received a 25 in methods last year.
If I'm interpreting my emailed results correctly, I got a D+ grade for unit 3, C for unit 4, and C for the exams. I was probably ranked around the middle of my cohort and I'd say that the class was average to below average in terms of overall strength.
As long as you've been actually doing the work assigned and are understanding most (or even half) of it, I'd say that it isn't too difficult to get at least a 30 in methods with a bit of work (and some practice exams), but that is just my experience, so take everything with a grain of salt. My results were a reflection of my lack of commitment to the subject and lack of asking questions when I really should have. I don't recall doing any practice exams for the subject (maybe I did one, I can't remember) and was behind for most of the year yet was still able to achieve a 25. Of course, don't aim for 25, aim for whatever you think is the highest you should, but know that a 25 in methods is generally not a difficult thing to achieve.
