If your playing HHM since you'd obtained a Silver Card. It really depends on how much Golds you spent. I'd recommend on probably cutting out buying silver weapons or any other expensive things in the secret shops as such. Arena Abusing would increase your fund. But it could seriously hurt your Tactics rating by A LOT, you could still use the arenas for your own cause such as getting more Golds. And about using the promotion items. Assuming you have more than the same promotion items, I would give one of the same promotion items to someone who'd probably would turned out good on HHM and sell the duplicated promotion items to increase your fund. For instance, if I were to have like 2 Hero Crest, I would simply giving to someone who'd benefit on HM such as Raven who is very useful on HHM because of the HM bonus that he'd gains as a enemy to start out and sell that other duplicated promotion item. I would probably recommend using some pre-promotes such as Pent, Geitz, and Harken who is very useful with the HM bonus as well since pre-promotes usually saves you the trouble of wasting a promotion items. And if you like Assassins' use Jaffar.
Also, I wouldn't use Nino when doing a Rank Run on HHM as well. Wasting tactics on training her and obviously wasting a promotion items on her.
*Note: more suggestion coming soon.