Sure, make sure to prepare adequately before traveling to enhance your wonderful experience. Here are some tips for your trip to Johor Bahru, Kuala Lumpur, and Kota Bharu:

Best Time to Visit:
Generally, Malaysia has a tropical climate, so it's warm and humid throughout the year. However, the best time to visit Johor Bahru, Kuala Lumpur, and Kota Bharu would be between March to October when rainfall is relatively less.

Route and Accessibility:
Kuala Lumpur is well connected by flights from all major provinces. From Kuala Lumpur, you can take a bus or a short flight to Johor Bahru. And from Johor Bahru, Kota Bharu is accessible by bus or flight.

Altitude and Acclimatization:
Being coastal cities, Johor Bahru, Kuala Lumpur, and Kota Bharu are at sea level, so altitude sickness is not a concern. But since the weather is usually tropical hot and humid, stay hydrated and take things slow if you are not used to such climates.

Accommodation and Booking:
All three cities offer a variety of accommodations — from luxury hotels to budget stays. Booking in advance is recommended, especially during school holidays and festive seasons as these places may get crowded.

Clothing and Essentials:
Lightweight, breathable clothing is best due to the weather. Rain gear can be helpful as sudden showers can be frequent. A high SPF sunscreen, insect repellants, and a hat would also be beneficial given the tropical climate.

Health and Safety:
Maintain personal safety while traveling. Be cautious of your belongings. Certain areas can get congested and might be prone to pick-pocketing. Make sure to have travel insurance in case of unexpected health issues.

Local Etiquette and Respect:
The Malaysian culture emphasizes harmony and respect for each other's religious practices. Please be respectful, especially in places of worship. Also, be sure to dress modestly when visiting religious sites.