Get the written instructions from the Manufacturer.
Top manufactures are very particular with electrical requirements.
Even the same manufacturer often has different requirements from hot tub to hot tub.
Read the serial number and verify you have the correct directions for your hot tub. If someone tells you all hot tubs are the same, keep reading.
Follow the NEC Code. Be advised that the Code calls for a disconnect within eyesight of the hot tub and may not be within 10 feet of the water.
Read the written directions and more importantly follow them. These are written for a reason and it is easier to do it right the first time than to have to do it second time.
Use an electrician that is licensed and follows manufactures hot tub requirements. A licensed contractor that is licensed is a good sign that you can rely on the work that they perform. When they ask for the manufacture requirements this sets them apart for most in their field.
Ask your salesperson for electrician suggestions. They know part of your hot tub experience is electrical, so they will point you in the right direction.
Any wiring outside the home, should be in conduit.