I apologize in advanced since I'm going to be posting everything silly that comes to mind so I will preface this by saying "try finding a gathering of people for stuff you like." I don't know how easy it is to find that sort of stuff, maybe start extending your social network by meeting friends-of-friends. Basically, you need to start finding excuses to meet (not see) more guys. I believe that's the best start.
Otherwise, I shall pass on the wise knowledge I have gained from watching anime...
First of all, if you're posting this from Seiren, get away from your computer and IMMEDIATELY find the nearest portal to Earth. There's simply not enough men on Seiren to guarantee that you'll even find one for yourself.
If you find yourself competing for a guy's attention, you must STEP BACK and analyze whether or not you're the primary love interest. Even secondary love interests can only succeed in blackmailing him into a date once.
If you believe yourself to be suitably powerful, you could always try shooting your way onto a rural planet and killing everybody you see until a guy you've never met manages to defeat you. He'd make a great husband.
3nodding Being a magical girl leaves you at a 50/50 chance of acquiring the guy of your dreams (unless you are the leader, which increases your chances to an only slightly better 75/25.)
Avoid tentacles. PERIOD. They'll only attract other women or guys who will already have girlfriends.
Join the bad guys and get sent undercover. Fun, exciting, and you'll live happily ever after with him. (Unless you're competing for his attention; see above "harem" avoidance.)
If joining the bad guys is not to your taste, you can always become a test candidate for a revolutionary battle machine / system. Then you'll get your choice of man... after 90% of the world population is gone but the war has ended, of course.
If you meet a guy whom you were childhood friends with, you must be the meek type or else he'll never get it. The more hyper, energetic, and silly you are, the more likely he'll choose a girl in a coma over you.
Devote yourself to god but still go on wild and crazy adventures (or put yourself in a church around where crazy adventures happen anyways.) You'll be certain to attract a man or two.