Allowing oneself to be vulnerable is a difficult thing, but in doing so we are showing our true selves and are more likely to find exactly what we want. I've often debated how much I feel guarding myself is necessary versus how much I'd rather just be myself right from the start, even if it comes at the risk losing someone I may have otherwise obtained as a contact, and I've come to this conclusion. I'd recommend leaning on the side being yourself and being vulnerable, on the notion that the person who is going to be best for you is going to accept you for who you are right from the start and if someone doesn't it might hurt initially, but that person likely wasn't worth it and you'll recover. I've lost a contact easily by making myself vulnerable, discussing a part of my past where I felt I made mistake, but acknowledging it was a mistake I would never make again. That person likely felt I couldn't be trusted, didn't want to take a chance on me, or felt it wasn't something I could be forgiven for, but whatever the case was it was the people I was open to about that same thing who accepted my fault, and acknowledged my will to become a better person that truly have become wonderful people to talk to.
One of my strongest contacts asked me a ton of questions in response to my first message, and rather than get deterred by it, I welcomed it, and responded with a large thoughtful message to which she responded in a similar manner. From that point our messages escalated and we got to know the bulk of one another's backgrounds within a week. Even now we maintain a strong connection, actively messaging one another about what's currently going on in our lives. The point I'm getting at is, this contact risked coming off as too strong or pushy, by asking as much as she did and by responding the way she did, but for the right person they won't see it as those things, they'll see it as a notable level of interest, and someone who genuinely knows what they're looking for. There are clear benefits to guarding oneself, though I think as another poster mentioned perhaps the usage of filters is a more effective means of finding what you're looking for with less risk of getting hurt. That said, I think the benefit of being able to be yourself around someone else, and get accepted for it is one of the greatest feelings you will ever experience.