Hello there! It's great to hear that you are planning to visit Lleida, Huesca, and Girona. I am here to help with some useful travel tips.

Best Time to Visit:
The best time to visit these Spanish cities is spring (April til June) and fall (September and October) as the weather is largely sunny yet mild. These periods also generally have fewer tourists as compared to the summer months.

Route and Accessibility:
You can reach Lleida, the first city in your list, by train or bus from Barcelona or Madrid. From Lleida, you can then take a bus or train to reach Huesca and Girona. The public transportation in Spain is good and well-connected, making these cities easy to reach.

Accommodation and Booking:
You will easily find hotels in all three cities ranging from budget to luxury. It is advisable to book in advance especially if you're traveling during peak season. You can book via online travel platforms or directly through hotel websites.

Clothing and Essentials:
Pack according to the season of your visit. If you're visiting during the best times (spring or fall), prepare to dress in layers. Some essentials would include a comfortable pair of walking shoes, sunscreen, a hat, sunglasses, a travel guide and a translation app for better communication.

Health and Safety:
Spain is a safe country to travel to, with low crime rates. However, like any place, it's always wise to stay vigilant, especially in crowded places. Don't forget to keep your travel insurance details handy, and have the contact numbers of local emergency services.

Local Etiquette and Respect:
Spanish culture is quite welcoming and relaxed. However, do keep in mind that a mid-afternoon siesta is common practice in some parts of Spain. Also, Spanish dining times are typically later than most other countries, with lunch time around 2-4pm and dinner starting as late as 9-10pm. Respect these local customs for a smooth and respectful interaction with the locals.