Beware of wood furniture, make sure it is made of seasoned and treated timber or else it will crack a few months later or you'll get boring insects tunneling into it. As for sofas and chairs, leather is also a no go as it will stick to your skin the moment you perspire. My favourite is rattan, cheap, looking good and fresh. Plastic looks cheap and gets out of shape. As for glass, i don't believe the glass used is thoughned. Going to personally buy your furniture will increase the price tag dramatically. What I normally do is to check out the piece, then send someone i trust inside the shop to agree a price and only then re-enter the shop. Do not be afraid to ask for discounts and seek for breakdown guarantees.
Union Jack's advise is first rate on all counts. A foreigner is well advised to look, evaluate and decide. Let a Filipino do the actual purchasing, with specific pre-purchase guidance on pricing, payment, delivery and guarantees. Even that is not a promise of success but it is better than you will do on your own.