This piece written by Cass Ball is great.
And you can safely replace “20s” with “any part of adulthood.”
Now’s the part where I physically restrain myself from quoting the entire thing:
“When I’m coming from a place of scarcity, a place where everything feels like it isn’t enough,I often feel that I’m insufficient without more experience, and therefore at risk of lowering my boundaries and putting myself in unsafe situations. Ironically, feeling like I’m “too much,” like my needs are a burden, is also a form of scarcity: it indicates that I don’t think I’m worthy of my needs being met. When I’m approaching sex from a place of abundance, I can value my needs and feel that they’re just right, and I therefore can communicate both pleasure and boundaries with equal confidence and clarity. Coming from a place of abundance means that I can be with another person while also being there for myself. The more I practice identifying how I’m feeling, the more vulnerable I can be and the more pleasure I can bring into my life.”
This is a thing I have thought a lot but not quite known how to say in words, so, yes! I don’t think you have to “love yourself before you can love anybody else” (I think you can be kind to others and to yourself without having a specific feeling) but really sitting with your feelings and asking yourself, why am I doing this, what do I want, do I feel comfortable and safe, do I trust this person, what would this look like if I let myself be enough just as I am, is a good practice for sexual (& etc.) relationships at any age and any experience level, and something that does not get discussed in either the “People who Do It are like pre-chewed gum that fell in dirty snow, do you want to go to HELL?” or the “Hey your body is going to be going through some changes! Try not to get pregnant, get anyone pregnant, and do your level best to prevent this array of sexually-transmitted infections. Any questions, by which I mean, questions about PIV sex that can be answered with the steely intellect of pure science? I have brought these condoms and bananas for demonstration” models of sex ed.
Here is another bunch of things I often think but did not know quite how to say, about how there are lots of kinds of love and connection in our life and romantic and/or sexual relationships are just one kind of human interaction, not a Whole Separate Branch of Being Alive:
“People often consider romantic relationships to be in a league of their own, completely separate from platonic friendships. But connection is connection, intimacy is intimacy, and the skills that make for healthy, happy friendships also apply to romantic and sexual relationships. If the idea of beginning a romantic or sexual relationship without romantic or sexual experience is scary, consider the journeys you’ve gone on with friends. Before I ever dated someone, I had already built complex, stable, emotional, life-affirming friendships. I had broken down, emerged through conflict, healed, laughed, broken up with, cuddled with, supported, and loved friends. I had learned to communicate and listen. Consider what your strengths already are and where you can grow.”
Cass Ball, people. Cass Ball. Pick that mic up off the floor so we can see you drop it again. 
If you’ve written to me asking how to approach sex and dating when you are shy and nervous about being inexperienced, I’m probably going to link you here and to Commander Logic’s wonderful post for the rest of recorded time.