mejo, mist..
yes, u can just go to the agency and they will tell you what to do. but then, there is really no standard per-se. the type of standard/service varies widely. some agencies are very detailed, they will tell u lots. some are very money-based.. so they sell by saying theirs is cheapest/best value for money etc. cheapest doesn't mean good, and neither does most expensive means good. so best is to shop around.
agency fees varies widely. from $0 to $600+. also depends on the experience of the maid. some are totally fresh (never been maid before). some have various experience in other countries.. then some have experience in SG. although usually it means higher agent-fees for more experienced maids, it may not necessarily be the case.. so again, best is to shop around.