We will stay in Hua Hin for a month.

Any recommodations where to rent a scooter or motorcycle?

Have read some horror stories about driving in Hua Hin and Thailand. But its easy way to visit in a shop or beach. You can easily explor some new locations nearby.

Or is it just more easy to take a taxi?

JK

There are just so many places to rent bikes you need not worry.

With regards to riding in Thailand it's no more an issue than anywhere else in the world. Don't act stupid, don't get drunk, don't speed etc etc. Just keep your eyes open and expect the unexpected and you'll be fine.

Having recently moved to Hua Hin I can state that the driving culture here takes a little getting used to viz wide and open roads free of potholes. You don't get this combination too often in Thailand!

Enjoy your stay - ride safe.

How much is the renting fee per month? petrol cost?

Renting in general: do's and don'ts before renting, on what to pay attention, docs required etc?

Thanks...

docs required etc?

Rental costs vary but expect to pay about 3000-3500/month. Insurance is optional. Wear a helmet or pay a fine.

Petrol costs what it costs, no bargains but small 125cc bikes take very little.

Ride with your eyes wide open.