Sure, here are some tips for your trip to Puerto Princesa, El Nido, and Coron, three amazingly beautiful sites in the Philippines:

Best Time to Visit:
The best time to visit is during the dry season, from December to May. January to April tends to be the busiest months, so book in advance to secure your accommodation and tours. Avoid the rainy season from June to November.

Route and Accessibility:
From Manila, you can directly reach Puerto Princesa by air. From there, you can take a bus or van ride to El Nido which takes about 6-7 hours. Finally, you can reach Coron from El Nido via a 4-hour ferry ride.

Altitude and Acclimatization:
The altitude is not high in any of these locations, so acclimatization isn't an issue.

Accommodation and Booking:
Multiple accommodations options are available ranging from budget hostels to luxury resorts. Booking in advance is advisable especially in peak travel season.

Clothing and Essentials:
Pack lightweight and breathable clothing, swimming gear, a hat and sunscreen for protection against the sun. A waterproof bag may also come in handy for boat trips.

Health and Safety:
Stay hydrated and use sunblock. Be very careful while swimming or snorkeling, and always follow the guidelines provided by your tour operators.

Local Etiquette and Respect:
In all places, showing respect to local customs and conventions is important. The Philippines is a conservative country so bear in mind to dress modestly, especially in rural areas. Avoid touching or damaging coral reefs and remember to not litter.