Well first things first, you can do all the generic quests like Waterfall, Witches House and tree gnome village to get your stats started at 30 or so.
Then you can start working on your stats through slayer preferbally. Try to get your combat stats at 70s and your mage at 75 then you could work on barrows, its probably one of the best early money makers out there, and it makes it even better if you can finish the hard morytania diaries.
If you need some quick cash to start, id say just try to get 45 runecrafting and do abyss runecrafting. I did it for 44-50 (needed it for a quest) and made a decent 1.3m in 3-4 hours.
As for armor, even at 80 stats i still rock the proselyte armor from recruitment drive, it has the best prayer bonus and its super cheap.
Or just do the good ol green dragons for the starter cash also, but they did change the requirements to use the shield (you need to start the dragon slayer quest to wear the shield, it was a way to stop green dragon bots early on.)
Personally, just set yourself some goals like i did. It keeps the game interesting and something to work towards. I'm working towards my Quest cape for quick access to a fairy ring so then i can get faster trips for runecrafting cosmic runes.
Edit: Witches House, not Witches Potion.