The hike up the Mist Trail and then down via John Muir Trail is tough but a doable hike for most people. It takes roughly a 3 hour round trip. Due to the crowd, JMT is a good option but it takes longer.
In the morning, consider having enough time to get to shuttle stop 16/Happy Isles. It might take you up to 40 min from one of the main Parking Lot. Shuttle stop 16 is like the stop outside Disneyland where everyone gets off. The trail becomes crowded by 11 am.
To avoid the crowd, plan to get early. A large number of people going up and down the narrow, misty part of the path is dangerous and annoying at the same time. Many people are in inappropriate footwear and push past people as if they are in a race. If you can’t get to the trail early, you should be respectful to others as this path belongs to everyone. It is not a race at the top. If you plan to hike farther than the footbridge, bring at least 2 liters of water with you. You can refill water at the footbridge water station. Bring some snacks with you as well.
Sturdy and tough footwear seems to be a necessity on the trail. However, most people you find there are wearing shoes as if they are here for a casual stroll in a mall. You will see people in flip flops, sandals with no amount of support whatsoever. You might even find a couple of people in crocs. What these people don’t realize is that this is a tough hike with an uneven surface and slippery terrain. You can twist your ankle just by looking at these people. You should make sure that you wear sturdy shoes with a good thread that can provide the necessary support and that the thread is not worn out and act like slippers. Be smart in making choices about your footwear.
Just because an unfit person got lucky and made it to the Vernal and Nevada Falls wearing flip flops while carrying just a single water bottle doesn’t mean that you should try and be that stupid too. Be smart to realize that this is not a casual walk in some city park.
This advice is very important for parents carrying babies with them. Your footwear choice will matter on the trail. You should not prefer to be seen stepping nervously in moby wraps with a baby on you.
Don’t swim or wade in the Merced River or swim in the Emerald Pool. No matter how cool it sounds, don’t go off the path, especially if you are in crappy footwear. The granite on the water’s edge is slippery and the current can be strong. The Emerald Pool is not far from the 300 ft drop of the Vernal Falls. So please don’t be an idiot.
Be smart and choose appropriate footwear for the trail. Carry water and snacks with you and be respectful towards others. Stick to the park rules and you will have a wonderful time hiking on the trail.