Some of my personal opinion as i also started this hobby around 3 months ago , base in sydney and have a relative and friends in Melbourne so a few domestic flight per year in general ,
I enjoy more when i fly with Qantas so that is my program of choice even thought i know that Velocity requires less point and less tax for ex : 6900 point $20 tax Velo vs 8000 QFF points and $32 tax for Sydney - Melbourne .
Internationally I need to Travel back to Asia once a year for family visit both Virgin and Qantas in my case can get what i need , With Qantas i can redeem via Cathay with a Hong Kong Transit directly via Qantas Points . Virgin will also give me some option as far as my research go with Singapore Airlines with a transit via Changi Airport . I have travel with both Cathay and SQ before and they are both great airlines but in term of Virgin you will need to convert Velocity - SQ Point before you can redeem at a rate of 1.35 : 1 so that will make things more complicated .
As a beginner i also looking at Amex Flexible program points as Keith point out here in Pointhacks , but i think it depend of your spending on credit card and other way to earn points , right now it is not for me . As the Platinum Edge Card i can get for a low annual fee on earn 3 points / $ via Supermarket earn and 2 points for petrol . unless you can put alot of spend into Supermarket and Petrol , i generally think Velo and Qantas program are easier to earn point via Amex cards for beginner with low monthly spend . ANZ AMex with 1.5 points / $ for almost everything .
My strategy as i earn points for last few month have been focus on 1 program and get a stack of points ( my bal is around 200,000 QFF Points now ) instead of 2 program and half half amount of points as my travel goals is business class trip redemption for 3 of us in 2017 - 2018 .