How to Have a Nice Voice
If you want to have a nice voice, strengthen your breath by taking 1 deep breath for each sentence you say, and releasing that breath slowly as you speak. Then, practice relaxing your voice by exaggerating the way you articulate words and opening your jaw more when you speak. At that point, you can start practicing with your pitch and tone by emphasizing different words in a sentence like, “I didn't steal the bike,” so it means different things.
Understand the different factors that make up a voice. The first step towards improving your voice is to get a good sense of what your voice is like now. There are six main categories that make up someone's vocal profile: Volume: How loud do you speak? Articulation: Do you slur your words or mumble? Voice quality: Is your voice nasally, breathy, or raspy? Overall pitch: Do you speak in a shrill, high tone or a deep, low pitch? Pitch variation: Do you speak in a monotone voice? Speed: Do you speak too quickly or slowly? Record your voice. To get a better sense of what your current voice is like, you need to record it and listen to it. This may not be fun, as a lot of people don't like the sound of their recorded voice, but this is much closer to what people actually hear when they listen to you. Record your voice using audio software like Garageband, and then play it back and listen for the details that make up your vocal profile, your volume, articulation, quality, pitch, variation, and speed. Recording and listening back to your voice will allow you to get an enlightening, objective look at what your really sound like to others. Take note of the flaws in your speaking voice, from mumbling, to filler words, to a nasally quality, and more. Write down everything you notice. Decide how you want your voice to be. Look at your notes about your voice and its weak spots. Then think about how you want your voice to be in comparison. Not everyone is going to have the same goal voice. For example, women with particularly low and raspy voices might want to raise their overall pitch and achieve a smoother vocal quality, while men with high, fast voices might want to slow down and deepen their speech. Improve your breathing. Speech starts with breathe, so good speech starts with good breathing. Ideally you want to breathe from your diaphragm, slowly and steadily, at all times. Start practicing by placing a hand on your stomach and breathing deeply so that you stomach rises and falls with each breathe. Practice this several times a day. Another breathing exercise you can do is to read a paragraph with a mix of long and short sentences. Use just one deep, single breathe for each sentence, exhaling gradually as you read out loud. Then take a breathe and start the next sentence. This is just an exercise to improve breathe strength. This isn't how you should try to talk normally. Slow down and lose the filler words. Faster speech will make you sound less confident, and will make you harder to understand. One way to improve the quality of your voice immediately is just to slow down. Practice by reading anything out loud, first with your normal speaking speed, and then slowed down. Another way to practice is to read off a list of numbers as if it were a long phone number, writing them in the air with your finger as you go. This is the ideal speed for natural, clear speech. Watch your pitches. Depending on where your natural pitch and pitch variety are right now, you may need to work on this a lot, or just a little. Work on your overall pitch by consciously trying to speak in a lower tone, as often as you can remember. It's important to do this gradually though, just around a half-tone lower at a time. Work on your pitch variety by injecting different pitches in your sentences to add interest and emotion. Two ways to practice this are the following exercises: Practice saying a two syllable word over and over with varying pitch changes. There are four types of pitch changes, rising pitch, falling pitch, rising up then down, and falling down then up. Repeat a sentence over and over and change which word gets the emphasis. For example, say "I didn't steal the bike," first by emphasizing that it wasn't you who stole the bike, then by emphasizing the "didn't," then by implying that you did something to the bike besides stealing it, and then by implying that you stole something other than the bike. Open your mouth and jaw more. Practice talking with a more relaxed mouth and jaw. The best way to do this is to practice on your own, exaggerating the normal movements of your face as you speak. Open your mouth wide when you make "oh" and "ah" sounds, and let your jaw move low. Add this to your daily voice practice routine. Learn exercises to relax your voice. If your voice isn't relaxed, you're going to be speaking from your throat instead of your diaphragm, and your voice will come out tense, harsh, and forced. Follow this method several times a day to relax your voice: Start by placing your hands on your throat and talking normally, noting any tightness in your throat and jaw. Make a big yawn and let your jaw fall as low as it will comfortably. End the yawn by saying "ho-hum." Continue the "hum" for several seconds with your lips shut, and as you do so, move your jaw from side to side and let it hang a little. Do this several times. Say the words "hang," "harm," "lane," "main," "lone," "loom." Exaggerate your facial movements as you do so. Yawn again whenever your throat gets a little tired. Use your fingers to softly knead your throat muscles. Relax your throat as your repeat the following sounds slowly: "nay," "nay," "nee," "no," "noo." Listen to the details of your voice. To really work on the details of your voice, you need to once again record yourself talking. Record yourself reciting a long paragraph out loud, doing your best to use a relaxed, slow, articulate voice. Then listen to this recording and make note of what areas your voice still falls short in. Practice saying those parts of the paragraph better, and then rerecord your voice. Compare the first recording to the second and note the improvements. Repeat this process until you are happy with the way your recorded voice sounds saying that paragraph. Do this exercise often to target the specific things about your voice that you want to improve the most. Listen to good speakers. Download some podcasts and audiobooks and take some time to listen to the way they speak. Listen carefully to the control they have over their voice, the way they articulate and move their pitch up and down. Part of developing a good voice is getting familiar with what a good voice sounds like. And, people naturally learn from example, so listening to good speakers regularly will start to have an effect on your own voice. Get elocution lessons. The best and most effective way to improve your voice is through professional voice coaching. Find a voice coach in your locality and book in for an assessment. Once you're seeing the coach, you'll discover new ways to project and improve your voice. Try drama or singing lessons. These can be a great way to improve the way that your voice comes across. Singing and speaking are very closely relating, so improvement in one area will carry over to improvement in the other. Search online for singing lessons near you. 
Understand the different factors that make up a voice. Record your voice. Decide how you want your voice to be. Improve your breathing. Slow down and lose the filler words. Watch your pitches. Open your mouth and jaw more. Learn exercises to relax your voice. Listen to the details of your voice. Listen to good speakers. Get elocution lessons. Try drama or singing lessons. 