There's no major advice that really comes to mind.
These are all the Maths course I know of that have had a lecture in MS.01, so you could call them the "biggies". I can recommend all to varying degrees:
HoM - Jeremy Gray is a good lecturer, but even so there's the odd pretty bloody dull lecture. Depends on whether you can be arsed to write three essays. They may sound like diddlers but you do have to work for it.
Topology - Colin Rourke (who always lectures it) can get his point across really well and gets good audience participation going, but your written notes might not be great. It's an interesting module when you can get your head around it.
Measure Theory - if lecturered by Cabreras, might be best avoided. I sat it anyway and he did get much better (so were he to lecture it again next year the course might be a lot better). It's a very love it/hate it course, just try it. I'll stick up for it though given I like the material
Complex Analysis - Thus far, a pile of piss. He's still not covered anything new, and spends half the lectures writing exercises on the boards that could just be whacked on a handout. He's far too quiet and writes far too small. The course is pissing a lot of people off, I believe, but it seems easy. Reminds me of Vector Analysis (with Jochen) last year, except for the amusing lecturer. Certainly, he's not left a great impression.
Knot Theory - An American guy took over the course for this year (whether it will return to the long-standing lecturer next year is anyone's guess), and he is pretty bloody good. He gets a tad confusing at times, but again there's some interesting material; he's enthusiastic, midly amusing and explains most things well, and again he get splenty of audience participation going.
As for other courses, Topics of Math Bio is probably best avoided if it's Kirklionis again (he's a nice enough guy, but a pretty poor lecturer that set absolutely no exercises or anything), FAI is an AMAZING module, QToODEs is a decent module but I must confess to not following a significant proportion of it at the time, Fractal Geometry is sort of annoying me (you'd think it's be great, especially with Anthony Manning, but it's really pretty boring at times), Galois Theory is pretty interesting and I'm taking it despite the fact that it looks hard, and FAII... Hm. It's not FAI, put it that way.