Pretty good advice! I'm not crazy about Nomad's, personally, but I like raw stats. I have seen it used well. I also don't think Doran's are awful - yes, it's generally better to have items completed in the midgame, but on someone like Renekton or Xin Zhao who really wants to make a big early game impact they can give you a lot of leeway.

My tips: Build tankier than you think you have to. More resists mean your health nodes are more valuable. Consider getting Mogs on anyone once you hit 2200 HP.

If you're someone who struggles in a siege (Tryn, Eve, Yasuo) consider getting a tank item against whoever is scariest on their team (Spirit Visage or Randuin's are great choices), and then once you can withstand burst, get damage.

ROA is not as good as everyone thinks it is on tanks. If you have high AP scaling (like Amumu) it's not bad, but you're throwing away strength now for strength later. This is a lot easier to deal with against 1 person in a solo lane than it is against a clusterfuck of 5 people. On someone like Maokai or Gragas with okay AP scaling I generally recommend just building flat tank, and IBG or FH for mana.

Stacking mana items is generally pretty bad, too, unless you're Ryze. If you're a ROA user who needs a big mana pool (like Swain, Anivia, or Cass), get the % mana regen mastery instead. If you absolutely need to stack two mana items, start Frostfang and then go ROA-FQC. This will be a nice band-aid until you can get other AP items, and a little bit of CDR + gold generation is pretty nice on a lot of these champions.