One of the biggest mistakes humans make when working with dogs is to have too high expectations for the dogs and too low expectations for themselves. Expecting a dog to climb a mountain without the appropriate safety equipment is setting him up for a big fall!
It's understandable for people to be keen to launch into life with their new canine best friend, explore all the dog walks and meet all their friends. But with a new rescue dog, it's so important to start off small and slow, setting the dog up for success rather than failure.
Work on building a bond with your dog and building up those 'mountaineering skills' (eg. recall, lead-walking, 'let's go' u-turns and other life skills) at home before you go outside and try to climb a mountain. Always remember your safety equipment (eg. double leads, long lead, secure harness, reeeaaally good treats) and take it one step at a time. Go home before your dog starts to struggle, better to return early but glorious than not at all!
Setting a dog up for success also means not putting them in environments that cause undue stress or danger. For instance, by giving them space when eating and sleeping, not leaving them unattended with other dogs until they've developed a solid bond, not leaving dogs alone with children, not leaving bones or other really high-value food stuffs lying around and creating safe spaces for your dog to retreat and be alone.
As with any journey, there will be ups and downs along the way. Progress is not linear and sometimes you and your dog may have to take a step back and re-assess. That's okay, as long as you are traveling together in the same direction. Advice and help is out there for anyone who needs it. Life is a journey best traveled with dogs, so make sure you don't lose yours along the way.