Absolutely, let's take these locations one by one:

Brezová Pod Bradlom:
Best Time to Visit:
The best time to enjoy this Slovakian town is from May to September when the weather is pleasant.
Route and Accessibility:
The nearest major international airport is Bratislava Airport. You can then make the rest of the journey via a rental car or public transport through trains or buses.
Altitude and Acclimatization:
Brezová Pod Bradlom is on the lower side in terms of altitude, so no special measures for acclimatization are needed.
Accommodation and Booking:
There are several Hotels, Guest Houses and private accommodations available - Booking ahead of time would be beneficial.
Clothing and Essentials:
Weather can vary, so layers are recommended. Also, pack a good pair of walking shoes and an umbrella or raincoat.
Health and Safety:
European Health Insurance Card holders can avail of necessary health services. Remember to get travel insurance.
Local Etiquette and Respect:
Be sure to respect local customs and traditions.

Myjava:
The advice for Myjava would be quite similar to that for Brezová Pod Bradlom, as they are relatively close and similar in terms of weather, accommodations and etiquette. Myjava is known for its folklore festival, so it would be ideal to visit during this event for a unique experience.

Stará Turá:
Again, similar conditions apply as for Brezová Pod Bradlom and Myjava. Stará Turá is known for its winery, so be sure to check that out when you visit.

Sklabina:
Best Time to Visit:
The best time to visit would be between May and September.
Route and Accessibility:
The nearest major Airport is Žilina Airport. From there, you can hire a rental car or take the train.
Altitude and Acclimatization:
The altitude in Sklabina is also relatively low, so no special acclimatization precautions are required.
Accommodation and Booking:
There are several accommodations options available, it's better to book in advance.
Clothing and Essentials:
During summer, the temperature can get pretty warm, so light clothing is recommended. Always pack an umbrella or raincoat as rain can be unexpected.
Health and Safety:
The general advice for health and safety including having appropriate travel insurance and EHIC applies here as well.
Local Etiquette and Respect:
The same respect for local customs and practices should be upheld here.

Enjoy your trip! Safe Travels!