if the task is rather repetitive then I suggest doing it yourself first, then document what you have done. This becomes a good standard that you can provide to the outsourced vendor to then complete for you.
You can also use this document to grade them against to ensure they are meeting your standards. This document does not have to be very formal.
For example recently I have been gathering contact information from a particular industry that has their contact information freely available on the internet. i performed the task myself and that enabled me to understand how many contacts i was able to document per hour. My documentation was captured by using a screen capture software called Jing Project (http://www.jingproject.com/
) which is free.
I took this documentation (video) and sourced a person to perform the task on ODesk.com.
I am now getting reliable help from the last 30 days and i have saved myself an average of 10 hours per week which has allowed me to focus on Marketing to this list - 10 clients closed so far.
BTW, the economy has never been so good for outsourcing as fewer projects are being created by corporations in the US. i have surveyed about 30 people from India, Pakistan, Philippines and Malaysia and the word is they have seen a huge drop in projects meaning less work for them in the long run.