To keep your fruits fresh cut them under running water to prevent from oxidisation.
This is the simplest technique of preventing fruits. Simply cover the slices of fresh fruits with plastic wrap in a proper way to protect it from oxidation.
To prevent from browning, you can keep your fresh-cut-fruit in a bowl of salt water. Soak all the slices of fruits for about 2 minutes after that drain all the water.
Take a bowl of water and add some honey. Then add fresh slices of fruits in this bowl for 30-40 seconds after that drain the water.
Citrus juice like, lemon juice or orange juice will help your fruits from browning. Firstly, place all the fruit slices in a tray then pour some lemon or orange juice over it. If you want to remove tangy flavour then you can wash it.
This is the easiest hack to prevent fruits from browning. Simply pour the soda water in a bowl of fresh slices of fruits and soaked them for 5 minutes then drain the soda water.
To keep your fruits fresh, keep them in glass container which has a lid and fill the container with cold water. After that place it in refrigerator, cold water prevent oxygen from reaching the fruits.