ive been using the sam davis book and summarising it. write down definitions and try to learn them. i usually end up doing this the night before, so its not as effective. it would work well if you plan on studying weeks before an exam.
likewise, there is a lot of content to cover, esp if u do the evo. of languages as the option. luckily i dont. developers view of hardware is so much easier
i think u will find that the main focus of the sdd exam is on scenarios, ticketing, railway system, etc. and u have to apply ur knowledge to the scenarios they throw at u.
best practice would be past papers and similar questions with worked solutions. learn the style of answering each question, this would include going back and revising the content(for eg- dfd's, feasibility study, ect)
anyways thats my 50 cents.