Hello! It sounds like an amazing trip to Portugal you are planning. Here are some travel tips for your visit to Lisbon, Porto, Coimbra, and Braga.

Best Time to Visit:
The best time to visit Portugal is during spring (March to June) and fall (September to November), when the weather is pleasantly warm with fewer tourists. The months of July and August can be crowded as it coincides with the local holidays.

Route and Accessibility:
Lisbon is a central hub for international flights, so it is convenient to start there. From Lisbon, it is easy to travel by train or bus to Porto, Coimbra and Braga. The railway network is extensive and efficient in Portugal.

Accommodation and Booking:
It's advisable to book your accommodations in advance, especially if you're traveling during the peak tourist season. There's a wide range of options available from budget hostels to luxury hotels in all these cities. You can make bookings via hotel websites or other online booking platforms.

Clothing and Essentials:
Casual attire is suitable for most places but remember to bring comfortable shoes for walking. The weather changes are quick, so it's also good to carry light layers. Don't forget your sunblock, sunglasses, and a hat for the sunny days.

Health and Safety:
Be sure to obtain travel insurance that covers health, accident and theft. Tap water is potable in all of Portugal and there are no particular health risks. Be aware of your belongings at crowded tourist spots as pickpocketing can happen.

Local Etiquette and Respect:
Portuguese people are quite polite and formal. It's customary to say 'Good Morning' (Bom Dia), 'Good Afternoon' (Boa Tarde), or 'Good Evening' (Boa Noite) based on the time of the day as a form of courtesy when you walk into any establishment.