Hi dags,
If you are looking to start a portfolio and your budget gets you a unit - then get a unit. Prolly better in my view to go for a house, if you can afford it, because land goes up in value and the building depreciates.
However, regarding renovations - in Melbourne as well as Sydney (where I am), it is the wrong part of the cycle to be doing renos and expecting a gain.
If you MUST do a reno, the simonjulie's advice of "If you can achieve market rent without having to do too much would be the ideal" is the way to go. This I have discovered from my recent experience also - so not just theory.
Cheers,