A lot of people hear the word "advertise" and think of more traditional advertising formats, like billboards or magazines or commercials - all generally inaccessible to the average person. But there are a lot of different ways to get the word out about your services that don't require huge projects or expenses. One of the simplest and cheapest ways to do it? Your own appearance! I've had colorful hair for a couple decades now, and any time anyone said anything to me about it - good or bad - I took that as an opportunity to give out my business card. I even gave one to a sheriff that pulled me over one time (I was driving...too slowly, lol). Any time anyone wants to talk to you about your hair, or about anyone's hair, really, that's the perfect time to mention your job and make a connection. Make sure you keep business cards on you at ALL times! And make sure to include your social media handles on them in addition to a name and business phone.
Which brings me to another advertising option - social media! While you CAN pay for sponsored posts on social media, this is rarely necessary. The primary function of having, say, an Instagram account, is to create a portfolio of your work. Sure, you can TELL people you're great at color, but wouldn't it be better to SHOW them? People are highly responsive to photos, so having a quick and handy resources to whip out or to direct them to from your business card is a great way to leave a lasting impression. Try to make vivids the focal point of your page - you WILL attract what you put out. Yes, this is tough when you're not doing a lot of vivids. That's where having models comes in.
Find a couple of "house models" - regular models that give you a lot, or complete, creative freedom to regularly (approximately every 4-6 weeks) create content in exchange for free hair services (teenagers and college students are great options for this - they are adventurous, young and beautiful, and broke, so they will love this arrangement!). Make their hair colorful to your little heart's content, then do a few different styles on it - straight, curled, braided, half up/half down, and maybe an updo or two if you're any good at them. Take a bunch of pictures of each style from multiple angles (looking straight ahead, from a 3/4 angle, looking over each shoulder, looking up, etc.), and BOOM, now you've got a ton of content to load up your portfolio. It's okay to share the same hair more than once! Once you start getting vivid clients, do the same with them if they are comfortable with it. Make it part of the appointment time; allow about 30 minutes afterward to take a bazillion pictures so that you have plenty of portfolio padding until you start getting a regular vivid clientele.
You can also use your models to bring in clientele for you. Make sure you mention in your deal that part of getting the free services means also helping spread the word! Give them a stack of your business cards to keep in their purse to hand out, and make sure they are familiar with your social media handles so they can make sure to mention them if necessary. People always wanna talk to you when you've got vivid color, so make sure they are stocked up with ways for commenters to get ahold of you! Even those people who comment who may not ever be a client (and this includes those making negative comments) probably know someone who WOULD be a client. Maybe that little old lady in line at the grocery store has a grandson who would like hair that matches his favorite football team...you just never know!
You also may make an effort to hang out where your market is. Even as vivid hair becomes more mainstream, the main demographic for it still largely consists of younger females, creative types, novelty seekers, and the like. Sure, you might see them here and there when you're out and about, but what about if you attend a Final Friday type art event? How about concerts - even small local bands and musical events? Bookstores, college campuses, art museums, festivals, and basically anywhere else you might run into the younger and quirkier artsy people in your area. Yes, this is a generalization, and doesn't mean other people can't or won't get colorful hair, which brings me to my other tried and true strategy:
USE YOUR EXISTING CLIENTELE!
You wouldn't believe how many people are out there that are secretly a little weird. But it can be really scary to deviate from the norm, to flip the bird to conformity, so most people don't do it. We hear little comments about it all the time: "Oh, I wish I could pull something like that off", "I'm not brave enough", "Maybe if I were 20 years younger...". This is your opportunity! These people are signaling that they are actually already open to the idea, but they are a little nervous about it. And what is making them nervous is that they are probably envisioning something incredibly dramatic compared to what they currently have, and it's my personal belief that any sort of huge dramatic change can be really stressful, even if it's exactly what we want. So the key to this is baby steps.
What does that look like? Well, it's not that complicated really - when they make these sort of comments, all you have to do is plant a little seed and say, "You don't have to do the whole enchilada! You can always just get a tiny peekaboo streak of your favorite color to feel it out..." Now the conversation is probably going to get a little more interesting! They've just been given an option that they can feel more comfortable with. Almost every person I've ever said this to has never considered a minimalist approach, and almost all of them are immediately willing to try it once they've considered it. If they are already highlighted or balayaged blonde, even better - not only can you just sneak a streak in during their 'normal process, but they are already getting a level of color maintenance that won't be a huge adjustment should they decide they actually want to continue getting vivids. In these instances, you can say something like, "Let me do a one time complimentary streak of the color of your choice, and if you hate it, it will just wash out back to your blonde. But if you love it, we can keep it up or maybe even try a different color next time."
Almost EVERYONE is down to at least try this. And a huge percentage of them will not only keep the color, but they also tend to get increasingly adventurous over time. Once they discover that they actually really like it, in addition to getting some positive feedback from their significant other/friends/family (that is, it doesn't turn into the big rejection fest that they were initially afraid of), they often begin requesting adding more colors, or trying out coloring all the tips, or putting in pieces in more visible sections, and so on.
It won't happen overnight, but if you give it a little time and develop a few some client growing habits here and there to help yourself out, you can get the clientele you want!