A tripod is a must to get any sort of clarity - any camera shake is magnified by a huge amount with macro lenses
As you're using digital my best advice would be simply to play - take loads of shots, experiment with different angles, depth of field etc and then look at the results instantly
I've always found that once you've roughly focused with the lens (and you have to manually focus, autofocus is hopeless here) then fine tuning is easier by moving either the lens or the subject
A focusing rack is really useful, but pricey - if you are keen on macro though they're worth it - I can recommend the Novoflex castel-mini, they're £93 from speedgraphic, but have a look around