Oil the cutters regulary with shredder oil then run a couple of sheets of paper through to spread the oil. Or use the no mess lubricating pouches. Ideally do this when you empty the bin or once a month.
Cross-cut shredders not only offer high security over strip-cut but also means you will need to empty the bin less often as the waste lies flat in the bin (when compared to a similar sized strip-cut shredder). If you are compositing your waste cross-cut will decompose faster.
Strip-cut (straight-cut) shredders will shred higher volumes of paper per pass and are less expenisve than similar sized cross-cut shredders.