Maybe an obvious thing, but it can be a bit fiddly tensioning the fan/ancillary belt and doing up the power steering pump bolts at the same time on my 200tdi, if you slide a pipe over the socket spanner and attach a small ratchet strap to the top you can make quite delicate adjustments to the tension, leaving both hands free for tightening the pump bolts.

Nice bit of 'think outside the box'. Or just get a friend/slave to help you