Currently, I am struggling with the capacity to reach orgasm. I have suspicions that the medication I'm on are causing SSRI related sexual dysfunction, but I can't know for certain. There are a bunch of things that can factor into the ability to reach climax, not the least of which being emotional and psychological stress.
It took me a really, really long time to figure out how to orgasm. I even stopped masturbating in my early to mid teens because I couldn't figure out what the point was, how there was possibly any payoff. I thought maybe I was doing something wrong or maybe something was wrong with me and it was just completely frustrating.
The addition of toys was helpful, but even then I never really climaxed. It just gave an added sort of pleasant hum.
I found that the key to my orgasms lie in my head. Vivid erotic fantasies combined with intense clitoral stimulation somehow clicked on the light in my head. I'd imagine the wet flick of a tongue and suddenly that little touch of a vibe would be infinitely more arousing.
I can't speak for experiences with a partner, because I've actually never had sex with a partner before. If, however, you spend any amount of time masturbating I would definitely suggest trying to add in sexy thoughts. It doesn't work for everyone but it definitely helped me.