Wearing braces for the first time can be a very disheartening experience. Questions like "Will I be able to pronounce that word?" Or "Will it sound strange?" Fortunately, with a little practice, you can also speak normally with the device.
Steps
Part 1 of 3: Basic Exercises

Step 1. Put the device on and repeat the alphabet
Say all the letters: A, B, C, D, etc. Repeat the whole alphabet a few times.

Step 2. Read a book aloud for ten minutes, and take note of any sounds you cannot reproduce
Then practice pronouncing these sounds until you can reproduce them correctly. It shouldn't take long.
Step 3. Count from one to one hundred
Do this a few times throughout the day.
Part 2 of 3: Various vocal exercises

Step 1. Sing songs

Step 2. Recite poems

Step 3. Have a phone chat with someone
So you can practice your voice, and they probably won't even notice your speech impediment!
Part 3 of 3: Reiteration

Step 1. Repeat the proposed exercises as many times as possible
Repeat these until you feel like you are speaking normally again.

Step 2. Always keep the appliance on, even if it bothers you
It may take a day, a week or even a few weeks, but you can be sure that the speech impediment will sooner or later wear off. Hurray!