Hiring a VA is a great investment, as long as he or she is an honest and efficient worker. I have hired many VAs in the past and with the bad ones, you would just end up wasting a lot of time in instructions and corrections. Consider arranging an extensive interview with some screening test before hiring anyone and don't forget to call their previous employers for feedback.
Most of my online tasks are outsourced. From building websites to write articles. If you know what are you doing just give procedures to your VA and check raports 1 time per week. YOu don't need verify his job every day. Just set up deadline in advance and to be honest you are good to complete tasks on time.