Absolutely! Romania is a beautiful country and the cities you're planning to visit, Oradea, Cluj-Napoca and Sibiu, each have their unique charms. Here are some travel tips for your journey:
Best Time to Visit:
The best time, generally, to visit Romania is during the late spring, summer, and early autumn, typically from April to October. However, for a less crowded experience, try hitting these cities in late spring (May and June) or early Fall (September).

Route and Accessibility:
Oradea, Cluj-Napoca and Sibiu are well-connected via road and rail network. You can take a train or bus from Oradea to Cluj-Napoca (around 3 hours), and from there to Sibiu (around 5 hours). Flights are also available from Cluj-Napoca to Sibiu.

Altitude and Acclimatization:
These cities are situated at low altitude so you are unlikely to experience any altitude sickness.

Accommodation and Booking:
All three cities offer a variety of accommodation options ranging from luxury hotels to budget guesthouses. Try to book your rooms in advance, especially if you're visiting during peak tourist season. Also, consider staying in historic parts of these cities to soak up the local vibe.

Clothing and Essentials:
Pack light because the weather is relatively warm from April to October. However, rainy days are quite common, so it is recommended to have an umbrella or raincoat. Also, remember to carry comfortable walking shoes as these cities are best explored on foot.

Health and Safety:
Romania is generally safe, but as in any city, be aware of your belongings and surroundings, especially in crowded places and at night. Consider carrying your important documents and extra cash in a money belt or hidden pouch.

Local Etiquette and Respect:
Romanians appreciate politeness, so remember to say "please" (va rog) and "thank you" (multumesc). Also, be respectful when visiting churches and monasteries; cover your shoulders and knees.

Enjoy your trip!