What to Pack - How to efficiently pack for every travel

When I do my bi-weekly travels (commute), I really don't need to pack much because I have what I need in my fiance's or parents' place. But to be safe, I always pack some extra clothes just in case I need them.

But for a week long vacation to a destination, that's a different story. I used to start packing for my travels 2 days in advance, maybe I procrastinate or got too comfortable with packing, I do it the day before the trip now. My rule of thumb is simple - pack what is absolutely necessary first.  Sure, you might say, "I'm planning to read my book on the flight", or "I'm going to the Caribbeans so I need my sunscreen."  However, the fact is that these times are NOT absolutely necessary - if  you can easily buy it during the trip, then it's not the first thing to go into your luggage/bag.

I'll categorize items into Types to show the degree of necessity for your travel.  You might need items in  Type 3 or 4 for sure, but they are easily accessible in case you forget to pack them.
I like to pack light so I do not recommend a lot of things to bring on the trip, so items in Type 5 are not my favorite things to bring.

Type 1 - Absolutely necessary

• Passport (International travel), Licensed ID (Domestic travel), Driver's License (Car Rental)
• Money (Bills and spare change), Credit Cards
• Prescribed Medicines (if taken regularly)
• Dietary Supplements (if taken regularly)
• Prescription Glasses/Sunglasses/Contact Lenses (and Solution. Yes you can buy solutions during the trip, but for International travels I prefer to use the brand I trust)
• Mobile Phone
• Chargers and adapters 
• Small Note (International Travel) - emergency numbers, number to call to report loss of credit card, addresses of your country's embassy, rental car company and hotels
• Few Undergarments and clothes (Yes you can buy during the trip, but you'll to wash it) 
• Security purses (to store passports etc)
• Medical Insurance cards

Type 2 - You'll need it and most likely you won't be buying during the trip

• Undergarments, clothes and pajamas for the entire trip
• Camera
• Comfortable walking shoes
• Non-prescription sunglasses (depending on the travel)
• Watch (an inexpensive one)
• Swimsuits  (depending on the travel)
• Fleece (spring/late summer/fall)
• Winter Gear - Gloves/Scarf/Hat (winter)
• Hiking Socks and Boots (for hiking of course)
• Rain Boots (a must in Venice)

Type 3 - You'll need it but you can easily buy during the trip, available in most airports:

• Toothbrush
• Toothpaste
• Contact Lenses cases
• Brush
• Toiletry Kits and Tools
• Flip Flops
• Ear plugs/Eye Mask
• Travel size Personal Hygiene Products
• Snacks

Type 4 - You might need it and you can easily buy during the trip

• Spare Battery
• Feminine Products (depending on timing of travel ;) can be Type 3)
• Sunscreen  (depending on the travel)
• Bug Repellent
• Travel Pillow
• Beach Towel (depending on the travel)
• First Aid
• Poncho (not Umbrella - much heavier)
• Packet of Tissue

Type 5 - Not recommend to bring

• Jewelries and expensive watches 
• Handbags or travel bags with no or broken zippers
• Large book (if you can't finish the reading during the flight times then it adds unnecessary weight to your travel)
• Fragrance (adds weight and slow down at the TSA checkpoint)
• Laptop for entertainment use (adds weight)
• Full size personal hygiene products (a lot of the skincare bottles/jars are heavy; and they could go above TSA limit and required to be checked in)
• Hair Dryer (most motels/hotels have it)
• Body Wash
• Shampoo
• Conditioner
• Body Lotion