Do your best not to let diction hold you back. If speaking clearly is a problem and people don't understand you, it's time to learn some tips. This is an issue which can be fixed. Your personal and professional life should not be affected by this. Too many people are hiding their talents and great ideas just because they are too embarrassed to speak up. The first step is to gain more self confidence.
If you are used to speak very fast than you need to change this. Slow down and the quality of your speech will get a lot better. This is one of the simplest tips to help you get a more clear speech. Another trick is to make short breaks whenever you change the topic.
You need to really speak up. If you are shy and cover your mouth with your hands or a book you will not succeed to speak clear. Stand up straight and talk with a louder voice. It's important to keep eye contact with the other person.
Always remember to articulate the word endings such as plural or past tense. This will make your speech more clear and without any grammatical errors. People are in a hurry and most of the time they fail to enunciate the word endings.
You can practice at home by yourself. Just make sure you're either alone when you do this or that other members of your household know what you're doing! To understand better where you need to work more you should record yourself. Try to read some simple sentences from a book.
Another trick to help you speak clear is to use simple and short words of just one or two syllables. If you're using long words it will be more difficult to speak clear. Try to find the correct equivalent. Improving the way you are speaking can be very easy. Keep in mind that communication is very important.