How have you had the best success for outsourcing:
1. VAs?
2. Individual gigs here or on another site?
3. Fiver??
1.- I've found that VAs are very good for doing tasks they are familiar with. Trying to train one is a waste of time. You don't need to. Linkwheels, manual social bookmarking, article writing and submission are easy to find. What I haven't been able to get is a VA who is familiarized with BMD. If you find a company where their VAs know how to work with it, please let me know.
Always go for an outsourcing company. They supervise and train (very basic) the VA. And, if he/she is not working, they are gonna replace it. Ask to talk with the supervisor in advance. Don't be shy, ask ALL the questions you have, even the stupid ones. Ask for daily reports the first week. Don't move to weekly till he gets it.
2.- In BHW I've found very good providers for "the whole package" jobs. Like "I'll write an article, spin it and post it on our 150 blogs network on 150 different IPs". That is a VERY good service. It worths the money and you have a lot of providers till you find 1 or 2 that fits your needs.
3.- For small services (200 bookmarks, Google +1, tweets, xrumer, etc.) Fiverr is the best choice. Make a list of gigs you like and start hiring. Don't be cheap, if you spend 100 and find 3-4 good providers... you have done a great research (it's gonna be easier if you know how to look).
As a tip, "top sellers" are usually (but not always) the best ones. The problem is that, most of the times, they don't want to be hired outside Fiverr. They are making money through gigs. Leave it like that. And, most of the time, the service they provide there are good enough.