Your first step should be to determine what carriers go from your home airport to Manila. Check out flights.google.com. Check your home airport and major gateways close to it. Then see what alliance those carriers participate in. For example, let's say you found Cathay Pacific was a possibility, or a combination of AA and Cathay. Both are part of OneWorld. That would mean you'd want miles on AA that you could then redeem for a combined AA/CX itinerary.

Philippine Airlines is not part of any major alliance.

In looking out a year, RT coach tickets are roughly $1K. That's a good benchmark to know if you need any repositioning flights in order to get to an airport where you can use miles onward. Sometimes it's easier to buy coach tickets than to redeem miles. Miles become more beneficial when you're looking for biz or F tickets, whose prices are often beyond the reach of many of us.