A few tips by (c) Agifall (direct link: http://agifall.com/ask-reference-letter/):

Tips

Number 1: Make sure you hand pick your reference. In many situations, he or she may have to speak with someone from HR, write a letter, or possibly fill out a questionnaire, so it is important that this person is solid and knows you well. Imagine, if you choose a reference and the person doesn’t know you, the recruiter may see right through this. You don’t want this happening.

Make sure to pick someone who knows of your achievements and can speak well about you.

Number 2: Give your reference the option of referring you or not. Make sure he or she doesn’t feel forced to do so. Imagine the person feels pressured and writes your reference letter. Do you think he or she will try their best? Doubt it! You don’t want it to be sloppy or lack the necessary impact or attention desired.

Number 3: Advise your reference. If you have used your reference for a particular position, make sure to let him or her know. Don’t let him be caught off guard. And, make sure you have his permission too.

Number 4: Be courteous. Managers, co-workers, and other people at the company don’t have to be your reference. But if you want them to, be courteous about it. You can explain why you think they would be a great reference and maybe you can even identify some specific points to really convince them.

Is Your Reference Short on Time?

Number 5: We can ask for a reference in writing, by email, or verbally. If you do it verbally, make sure you follow up with your talk in an email. Now, don’t let your reference just free write the letter, give him some info. Tell him about the company, position even the job description. Send him your updated background and an up-to-date CV. You may even go as far as writing why you think you are a great fit for the position. You reference can then use that.

Number 6: Some people may not agree with this one, but you could provide your reference with a suggested template of what to write along with bullet points. Let’s face it, your reference may not have many hours or days to ponder the reference letter, and you can’t afford to have a mediocre one, so do both of yourselves a favor, create a template and add some bullet points to it. You could even go as far as writing it and then asking him to make adjustments as he sees fit.

Now, for our last step, let’s just take a look at a brief reference request.

Example Reference Letter Request

Dear (reference’s name),

I am in the process of looking for a new position as a Product Manager and am hoping that you could be one of my references.

Having worked with you for five years at (company), I am certain that you can provide the recruiters with accurate information about my skillsets and experiences, thus increasing my chances of getting the job.

I have attached my resume, a copy of the job description, and a short doc with bullet points of why I feel like I am an excellent candidate for the position.  Please let me know if you need any more information.

Thank you once again for your consideration.

Kind regards,

(Name)

(Phone number)

(other contact info if necessary)