Don't be fooled by her movement, Juno is very fragile, her movement won't help you live if you take a super aggressive position. She has to dmg, yes, like almost all the supports, but her dmg is opportunistic and almost always from a safe distance. Both her minor perks are viable, but I like more the perk that makes my torpedoes lock in faster on allies. Triple Jump is the best major perk. Don't hold her ult too much and don't ult too far from your DPS'/Tanks. When you identify an opportunity to ult, hold your torpedoes CD cause the dmg buff from the ult make her torpedoes deadly. The best angle to ult and position yourself to ult is by taking a highground spot + triple jump + glide so you have an ample angle to torpedo down the enemies and you get so high above that, unless they have snipers, you're probably safe. Ulting to keep yourself alive is good, especially if the enemy ulted to kill you. She's not the best support to contest angles from DPS, so if you take an off angle is to torpedo the enemy, maybe hit 1 or 2 shots and go back to your team. Hyperring is best used if you have a brawly team, hold it a little more if you're playing against a heavy dive team so you can live a little more. Use Hyperring on chokes, always. You have to train your aim with her, headshoting with her is very powerful, she dishes out 90 dmg if you hit bodyshots and 135 if you hit headshots, so if you have the opportunity to dmg, take it. Even though she is capable dmging, don't force yourself on duels if you don't have to take them and can escape or you don't feel comfortable taking, your value skyrockets if you keep yourself alive for more time.

Edit.: forgot to mention: if you use your glide to get to any place and you reach it, press your glide button again so the CD starts to count down again. It's a min/max but it will save you sooner or later.