I do not advise that you draft your own release. Rather, you may wish to have a release generated by an attorney who carries malpractice to protect you in case the letter does not hold up in court. I have written an article on the Borat release form, that may be of interest.
Generally speaking, California Civil Code section 3344 controls the right of publicity (use of a person's name for commercial use), but other statutes and laws may also apply.
See, e.g., 3344 (a) "Any person who knowingly uses another's name, voice, signature, photograph, or likeness, in any manner, on or in products, merchandise, or goods, or for purposes of advertising or selling, or soliciting purchases of, products, merchandise, goods or services, without such person's prior consent, or, in the case of a minor, the prior consent of his parent or legal guardian, shall be liable for any damages sustained by the person or persons injured as a result thereof. In addition, in any action brought under this section, the person who violated the section shall be liable to the injured party or parties in an amount equal to the greater of seven hundred fifty dollars ($750) or the actual damages suffered by him or her as a result of the unauthorized use, and any profits from the unauthorized use that are attributable to the use and are not taken into account in computing the actual damages. In establishing such profits, the injured party or parties are required to present proof only of the gross revenue attributable to such use, and the person who violated this section is required to prove his or her deductible expenses. Punitive damages may also be awarded to the injured party or parties. The prevailing party in any action under this section shall also be entitled to attorney's fees and costs."
This answer is not a substitute for legal advice and it does not create an attorney-client relationship. Seek the advice of a licensed attorney before taking any action that may affect your rights
"You have been using my name and image in your monthly poker magazine work my full consent. I like it, and so I give you full right to use my name and image in your e book without any compensation. Good Luck with your book."
Short is often better. Long is usually because of added exceptions, which do not help you.
Of course, if you are smart you will see a lawyer so you also get your work properly protected do you can profit from it without hassles.
I am not your lawyer and you are not my client. Free advice here is without recourse and any reliance thereupon is at your sole risk. This is done without compensation as a free public service. I am licensed in IL, MO, TX and I am a Reg. Pat. Atty. so advice in any other jurisdiction is strictly general advice and should be confirmed with an attorney licensed in that jurisdiction.
If you're in the UK and this is UK article for a UK e-book, you need to consult a lawyer licensed in the UK because laws are site-specific, and even federal laws like those for copyrights and trademarks are territorial. The publicity rights law cited by my colleague is a CA law, and some states have adopted their own similar law, but you need to look at the law that governs where you are and where your target audience is.
Regardless, I'm not sure why any 1st names would require licenses, or why their "characters" would be used and recognizable in an article about poker.
Avvo doesn't pay us for these responses, and I'm not your lawyer just because I answer this question or respond to any follow-up comments. If you want to hire me, please contact me. Otherwise, please don't expect a further response. We need an actual written agreement to form an attorney-client relationship. I'm only licensed in CA and you shouldn't rely on this answer, since each state has different laws, each situation is fact specific, and it's impossible to evaluate a legal problem without a comprehensive consultation and review of all the facts and documents at issue.
Let me ask you one basic question: why is it important to use their real names? If you use their real names you are opening yourself up to name appropriation and invasion of privacy claims. The names themselves do not add anything to the work, I feel certain. If I were you I would change their names in an effort to preserve their privacy and your relationships. While you are at it, think about making them amalgams of different characters or at least adding some fiction- you know, write. That way you are not appropriating their exact lives in a way that will be obvious to their loved ones and offensive to them as friends who have shared intimate and what they thought were private times with you.
If you ask for a release, what are you going to do if they say no? Why are you asking for a possible dispute with close friends? BTW, most self published works make no money to speak of so think about what you stand to gain and balance that against what you stand to lose by taking this course of action.
I know this is not exactly the advice that you asked for, but I am not sure that you are considering all the ramifications here.