You need to plan your trips.
You need to know good, safe places to bikejor and skijor. You can still explore, but having a good idea of the risks you can encounter is wise.
Know your route. Maintaining control when going downhill is hard. The steeper it is and the fresher the dogs, the harder it is to avoid an accident. Icy roads or snow with an ice crust are particularly difficult. It's best to plan your route so you are going up the steep part and down on gentle slopes if you can. If you must go down a steep section, try to set up the route so you save that to end of a run when the dogs are slower. I don't bikejor on icy roads.
You must remember to bring your critical equipment. Harnesses, gang lines are necessary for your team to go. Water and first aid equipment is important for the dogs safety. A helmet, goggles and gloves are important for your safety. I keep most of my important equipment in a big plastic tub. The only other thing I need to remember is food, water, skis, poles and boots, or a bike, along with suitable clothing. Navigation equipment may also be important on new or confusing routes.
Where's the nearest emergency vet clinic? (Do a web search!) How would you get a collapsed dog to your car and to the clinic? (Do you have a cell phone and can you call a friend?)