My 2 cents or centavo worth
Safe ? Well, you don't need to leave all at room. Get a 30$ nokia phone, and upon landing, get a local sim card - it's just 30 peso for SIM. and a 300 peso load will last for a while, and help you to plan private deals
And carrying a local cheap phone is good for saying hello to curious mall girls
And you can also pretend to ask how to pasaload or top up if you see a local girl. Better lose a cheap phone than an expensive phone if it's a scam.
And for other stuff, well, different people have different safety plans - for me, I avoid crowds, kids, and never keep anything in the back pocket, especially in Manila and AC. A slim wallet just to keep a copy of your IC/Passport and some $ is good. Strictly speaking, in Philippines law, Foreigners must carry original identification at all times, but that law dont' apply to locals, as locals don't have any national ID- most girls carry their work ID, or previous employer's ID, or postal Id or even home made IDs and it's accepted. Not for foreigners - keeping a copy for me is enough till now as when asked for ID, I wasn't challenged. I am sure they will insist on original ID / passport if you challenge the cops or they see you as $$$$$$.
For me, I never felt I need to hide money in underwear, as I have seen some ang moh do - when the bill comes, they pull down their pants to pull out money.
If you are threatened with a gun or knife (rare in AC anyway) - hiding in underwear or up your ass and all will not save you. Those robbers will not believe your story of 'walang pera' and may prefer to kill you and search you, than wait for you to tell them you have money up your ass.
On the other hand, just keeping in slim belt pouch is good enough.