^Nice thread you started tiggerlily. But don't you wish meron na nito before we undertook our projects?

To add lang:
Plan the interior fit outs as early as possible to avoid patibag ng walls, etc. Even the lay out of the cabinets, and the details - the drawers, the rods, etc. specify what you want.
As for finishing details, I will not preach that you stick to the allotted budget as much as possible. This stage is really challenging, because you tend to think "Para isang pagawaan na lang." "Andito na rin, might as well, spend a little extra." For me, get the most cost-effective finishing details for your non-negotiables or at the very least for the areas that are high in your priority list. I'd go for those with warranty, with a good track record for quality or after-sales service, etc.
Those extra pesos might be your best investment in the long run. But of course, mag-research at mag-research, at mag-canvass ng mag-canvass. First hand accounts would be your best sources. Ask around and get referrals.
Haggle for the best price, always. In every aspect of the construction and for every item na bibilhin. It does not hurt to try di ba?
If you can buy several items from one source, try to negotiate for the best price. Your business would be always welcome. Kita rin nila yun ah!
You will need time and effort talaga. If you want makatipid, magtitiyaga ka talaga.