Luggage and bags:
Torch (pocket size)- Electricity cuts are common... You will nearly always find yourself on the way up stairs as it cuts out...
Clothing/Shoes/Weather Gear: As said before, towel... this can also be used for a makeshift cover on long boat trips.
Toiletries and Medical Supplies: Ear plugs if you dont like being woke up at 4pm as the local bird life seems to be set to 'loud'..
Photo Equipment: Lots of spare memory for camera - Philippinos love being in and taking lots of pictures..
Miscellaneous: Unlock you phone when at home and buy a pinoy SIM there. Much cheaper.
Taxi drivers are a great source of information if you are looking to find some live music.
Dont use hotels, find pension houses, they tend to be much cheaper and a joy to stay in.
Dont take Scottish money and expect to be able to change it there.. You can, but its not easy..
clothes are so cheap to buy in the philippines, you dont need to bring many at all. you can buy a t-shirt for £1 - £2 and a good pair of shorts for £3 too if you shop around. footwear comes just as cheap. No need to buy a rain coat, its better to buy a small umbrella.
Toiletries and Medical Supplies: take plenty of cream for bites. repellants tend not to work in my experience so you need things to take away the itch and soreness. Something to steralize the water that you wash your teeth with may be useful
Photo Equipment: dont forget camera batteries. Though batteries in AA or AAA are cheap there, other sizes may be difficult to find.
Miscellaneous: a towel is always useful. in case of a heavy downpour you may need a rub down, also there are hotels with no towels.