1. Be honest
If people discover you lie, you will surely lose the job opportunity you aim for.
2. Ask the right person
When asking for a professional reference you should choose someone who knows your work well, and who endorses your performance and ethics.
3. Avoid mentioning your current employer
If you are still not sure that you will get the new job you are applying for, avoid drawing unnecessary attention: instead asking your boss for a reference, ask one of your coworkers who promises to be discrete.
4. Never ask your relatives for a reference
Choose instead someone who has positive things to say about you: it can be one of your former bosses or coworkers.
5. Contact your reference beforehand
Asking for a professional reference when you are in a hurry might reflect poorly on you: the person you ask might not instantly remember you or your previous work, which could affect your chances of getting the job.
6. Companies can also be a reference
If your former boss and colleagues no longer work for your previous company they can help you to ask the company for a reference or directly endorse your previous experience.