"How do I sell my husband, wife, parent, etc. on Primal?"
The short answer is that you probably can't.
The most important thing is to live ancestrally yourself. If you do, people will eventually notice changes and ask you how you do it. No amount of persuasion will work unless you walk your talk. If you personally haven't had any dramatic change, e.g. you just needed to lose some weight and you just feel a lot better on the blueprint, you could point the person who you want to sell to success stories.
Don't rant. Unless you are trying to convince someone in desperate need of primal (e.g. with a life-threatening illness), don't be a missionary. Don't get on a soapbox. It almost certainly won't work.
Even if you think 99% of the food in a typical grocery store is poisonous, frankenfood crap, don't say it. Don't tell the person that their favorite comfort food is tasteless, disgusting crap.
Do not tell the person you want to convince that cauliflower is a good substitute for rice or mashed potatoes. Cauliflower is delicious, especially roasted. Maybe you think it is a good substitute for rice and mashed potatoes. To the average person, saying things like this just makes you look like a nut case.
Don't go off on not shampooing or using deodorant. That isn't going to make a good impression on most people.
Wearing minimalist shoes, or going barefoot, is a wonderful concept that I follow. It is not core primal.
Observe how Mark Sisson goes about promoting primal. No rants, sense of humor, plenty of information to back up what he says, reasonable and forgiving of human nature.
Catch people when they are receptive, like when they are making New Year's resolutions. Those will probably involve signing up for a years gym membership with the intent to do aerobics every day, eat an unsustainably restrictive diet, and otherwise set themselves up for failure. How about saying "It seems like you do this every year and it never works." (They nod.) "This year, how about trying something you can live with?" In the winter, when people have miserable colds and flus, how about saying "I rarely get a cold/flu anymore, and when I do, it is mild." "How?" they ask. "I get lots of vitamin D."
In general, catch people when they feel hopeless about everything they have tried or realize they have let themselves go to pot.
You might make people feel receptive with tough love. Not my style but it might work for you. "If you are not going to take care of your health, hurry up and die of a heart attack while I'm young enough to date other men."
If the person (usually male) is an ex-combat soldier, college athlete, macho, watches extreme cage-fighting or similar, and has a good sense of humor, you might try guy insult humor. "WTF is with the spare tire?" Actually, if they are receptive, you might as well ignore the rest of this page and introduce them to the whole "me caveman" Grok thing.
For most people, forget cavemen! The caveman theme may highly motivate you. If so, great! It won't motivate 95% of the people you want to convince. They find it lame, gimmicky, obnoxious and irrelevant to their lives. They have images in their minds of Flintstones, old B movies, and cartoons. There are more accessible images of paleolithic hunters and gatherers, like American Indians, whom nearly everyone admires.
Another way to make primal accessible is to say it isn't very different from how most people lived 100+ years ago when most people lived on family farms. Aside from eating grains, they lived very primally. The person you are trying to convince probably has or had an elderly relative who ate bacon and eggs every day and saved the grease to cook with, and lived to be 95.
Focus on the key tenets of primal. Eliminating junk foods, sugar, seed oils and wheat. Getting enough vitamin D. Becoming more physically active. Getting more saturated fat. If the person does those things, they will start to feel better.
Make a really delicious primal food for them. I am cautious about sneaking primal foods into someone's diet, especially if they have told you they do not want to eat something like liver, but there are plenty of ways to do it in an ethical way, e.g. shifting from using vegetable oil to coconut oil and butter.
Invite the person to do something active with you. Going for a walk, shooting hoops, dancing, whatever you think would engage them.
In general, do not refer people to lots of different takes on paleo until they solidly understand the Primal Blueprint (or whatever you choose) and have started living it. You may only cause confusion.
Be careful about referring someone to Mark's Daily Apple, wonderful as it is. Refer them to specific posts that will be helpful. If you refer them directly to MDA, they may be freaked out by a post by Mark on how to cook a goat's head.
Don't just hand someone a whole stack of research UNTIL the person has shown serious interest in primal and has questions. Same with The Primal Blueprint. They will just give it back to you two weeks later saying "It's 'interesting' but I don't want to be a caveman."
Even if you try all these suggestions, they may not work. Say the Serenity Prayer, or your version of it (not necessarily to a higher power - I say the pagan version) and let go.