Pack the essentials: undergarments, shoes, a set or two of regular clothes, entertainment, medication and, for longer flights, basic toiletries. Some people fly as if they may never see their luggage again – and that has some merit. Keep in your carry-on the minimum of what you need to survive should you lose your luggage.  Double-check TSA guidelines before packing something in your carry-on. You don't want to have to throw anything away. Make sure to take all your medication and everything you need to be comfortable. Prescription and non-prescription medication are allowed. It’s easier to get extra liquids through security if they’re medically needed, like with saline solution. In order to cut down on the amount of clothes to pack, choose items that are interchangeable. Stick to a few items that all go together, rather than completely separate outfits. Use accessories to spice up an outfit. For example, scarves are small and easy to pack, and can be used as a scarf, headband, or even a belt. Take your swimsuit if you are traveling by air, put it within your vacation gear, especially if you are a woman. If your bags are lost when traveling by air, most items (such as shorts or T-shirts) can usually be purchased at your destination. However, if your bags are lost, swimsuits for women can be hard to shop for. If you do not have your swimsuit you may miss out on the beach, hot tub, or other vacation fun. Anything valuable should come with you in your carry-on. On the off-chance your luggage gets lost or damaged, your carry on should not leave your possession. If you'd be heartbroken if you lost it, take it in your carry-on if you take it at all.  For safety reasons, any electronic items with lithium ion batteries, including most laptops, smartphones, tablets, should be packed into your carry on instead of checked luggage whenever possible, per FAA recommendations. In addition, power banks and spare lithium ion batteries should always go into your carry on instead of checked luggage. Pack large electronics last, so they are easily accessible. You will not need to go digging around when time is of the essence. This is good for two reasons:  You will probably get bored on your flight, even if it is only half an hour, and having your electronics together lets you know where everything is so you can access your iPod, iPad, Kindle, or whatever else you need as quickly and easily as possible. The TSA requires electronics to be screened – when they are all in the same place and easy for the agents to see, you won’t be the one holding up the line at security. In order to get on the plane, you need identification, such as a passport or driver’s license.  Do not forget your ATM card and your credit card or AAA card. However, it is probably a good idea NOT to take every piece of plastic you own because you run the risk of losing the cards. In an easily accessible pocket of your carry-on luggage, store your flight information: the airline, the flight number, your confirmation code, and the flight details.  This comes in handy at the self-service check-in kiosks that so many airlines provide now at the airport. You may not need to pack much, if any. Your Aunt Maria probably has shampoo, for instance, and Peru will likely have toothpaste. It may take an extra stop at a store on your travels, but by avoiding tons of bottles, lotions, and tubes, you save space for other, more important things. If you do bring toiletries, in the United States the 3-1-1 TSA regulations still applies.  You can fill as many 3 oz bottles of toiletries (100 ml) as you want into ‘’one’’ quart-size plastic ziplock bag (limit one per flyer), but you have to take out the bag at security screening.  Go to www.tsa.gov for the full rules and regulations. Sometimes flights can cause headaches, so have a pack ready just in case this happens to be that one. A few things you may want to pack:  Painkillers Bandages A sedative (if you are a nervous traveler) Anti-nausea medication Chewing gum (for air pressure changes) Tissues Earplugs (good for travel in general) Medication for anything you are prone to, such as allergies. Remember you are not charged for the clothes you wear traveling, so dress with that in mind. Dress in layers so you can bring more with you. Instead of a T-shirt and jacket, wear a T-shirt under a long sleeved top under a sweatshirt, for example. Wear your hiking shoes and pack your flip-flops, especially when you are traveling for business.

Summary: Pack it in your carry-on if you cannot live without it. Pack valuables in your carry-on. Pack your electronics together. Make sure you have your documents. Do you really need toiletries? Have a first aid kit with the basics, especially pain medication. Wear it, do not pack it.


In a simple substitution cipher, you can assigning letter values to other letters. For example, A may equal C and and F might equal J. Make sure you don’t choose easy combinations like A = B or A = Z. They’ll be easily broken.  Make decoder rings. Those decoder rings you got in a box of cereal years ago may come in handy, but you can make your own too if you want. Write your letters, A through Z, in a large circle. Then, write the substituted letters inside the large circle to form their own smaller circle. Now you’ll have a key for your cipher. Randomize the cipher. Once you’ve got your keys and your friends have theirs too, you can cut out both rings from the paper. Turn the smaller ring inside the larger outer ring to create new substitutions. When you pass your note, write what A equals, and the reader will know where to set their rings. To make a slightly more complicated substitution cipher, you can make your own simple symbols to stand in for letters. The more each symbol looks different than the letter it represents, the harder the code will be to crack. Make sure each symbol is also simple and easy to draw quickly.  Create a key for your new language. Make a master key that shows which letter matches up with each symbol. As you practice writing in your new script, you’ll become more familiar with the symbols, but you’ll need a key at first to remember which is which. Share the key with friends. Your language won’t be of much use if only you can read the notes you pass! Share the key with your friends, advising them to keep it safe so that no one else finds and learns the symbols. Write your messages in the new language. Practice the symbols until you can read and write them as quickly as your native language. It’ll take a while, but you’ll get to know the symbols well over time. For example, swap A with (α) Alpha, B with (β) Beta, C with (Χ) Chi, etc. from the Greek alphabet..  Use similar characters for missing letters. Some foreign alphabets may not contain all the letters in your language. Greek doesn't have Y, but there's a visually similar Upsilon (Y in capitals), so you might use that instead. Make sure your reader knows that you’re going to be substituting some letters for others not in the language. Test some examples.  For example: "See you tonight" becomes "ΣΕΕ ΤΗΟΥ ΤΟΝΙΓΗΤ,” with “you” subbed out for “thou” because Greek doesn’t have a character for “Y”. Numbers tend to stick out in messages with a lot of text, so try to find a better way to to hide them in your cipher. For example, replace the "8" in "See you tonight, 8 o'clock" with "√(128/2)". The 8 is replaced by a simple math: the square root of (128/2=64)=8. It’s relatively easy to crack a substitution code, because you’re still using your native language and only swapping out the letters for other letters or symbols. Words like “and”, “you” and “the”, which will show up frequently in your messages, and can be found out and used to piece together parts of a key. Common letters like E, T and A also help code-breakers to decipher your message.
Summary: Substitute letters for other letters. Substitute your own symbols for letters. Substitute letters from another language. Substitute equations for numbers. Be aware that substitution ciphers can be broken.