The regular dating scene
The first is, honestly, just to date as anyone else would, and you very well might end up in a relationship with someone kinky. There are no hard and fast statistics, but it is estimated that about 10% of people (this is in North America, and I am not sure how far you can generalize this) would classify themselves kinky. These people tend to be into lighter bondage, silk blindfolds, maybe some fuzzy handcuffs, and what would be generally classified as lighter kink. Then, 10% of this group (so 1% of the overall population) is really kinky; this includes the whole array of BDSM (bondage, latex, pegging, etc.). So, honestly, your odds of finding someone kinky are not horrible. Also, in my experience, people like to talk about sex, so it becomes pretty easy to bring up BDSM (and your sexual adventures), and to see if you have any common ground with someone. This is obviously quite personal, and it does depend on your social circle. Some people are very conservative when they talk about sex. This is how I met my girlfriend, though, and I will discuss it in more detail in part 3.
The second thing you can do is just bring up BDSM with a non-kinky individual, trying to integrate kinky things into your sex life. Some people refer to this as “converting” their vanilla partner into a kinky partner. There are some people who are always interested in BDSM, but there are others who learn about it and like it. It can require exposure for someone to learn about it before they like it. Some people will never change, and some people will never like it -- but, there are some who will. So, if you current partner is not kinky, bring it up; give it a shot, they might surprise you. My girlfriend liked some lighter kink initially, but after I have exposed her to a lot of other things, she has really expanded her interests. We partake in lots of things she initially was not interested in. I do not think you should ever force it on your partner and expect them to change, but certain people will pick it up and like it.
Fetlife.com
FetLife.com can be thought of as kinky Facebook. It is NOT a dating site, but it can be used to meet people with similar interests, and it can help you get involved in your local BDSM community. FetLife is set up around groups, so most larger centers will have a group. For example, you could search "New York," and you will see that multiple groups will come up. Some of these groups will have specialized interests, whereas some of them will be very broad and generic. You can then join groups, get to know people, and get involved in the local community. Most people will not respond to dating requests on FetLife, though. What most people use it for is finding people with common interests. They then hang out (often at a munch, which will be discussed in the next part of this series), and then ask people out in person if they like them. FetLife can be thought of as a tool to find a group of friends that share a common kinky interest, but relationships/dating/play can stem from that. FetLife does have groups that are for dating (classifieds), so you can date on it. FetLife purposely makes dating hard, though; you cannot search female dominants in New York, for example. You have to join groups and meet people to do this. FetLife is commonly referred to as the best place to start. There are a lot of great people, a lot of great information on how to do things safely, and then there are groups you can join to meet people in real life. I would recommend making an account and exploring FetLife. It is probably the best place to start.
OKCupid.com
There are regular dating sites, too, such as OKCupid.com. On sites like this, people just add BDSM as part of their profile. So, just using normal dating websites and making it clear that you have certain sexual interests you want fulfilled can be quite effective. It is fairly easy to come across profiles where people disclose this information. Some people will not be upfront, so you might need to talk to someone for a bit before you ask if they are into BDSM.
Those are the three places I know of where you can search for other kinky individuals. If you have any questions or concerns, feel free to ask in the comments.