In one word, to seduce, keep, hold, attract a Leo, you must give him or her flattery. This is what Leo thrives on, eats it up like candy. Leo feels important when you flatter him or her. This doesn't mean that Leo is particularly filled with conceit, filled with pride, but Leo really needs to feel that he or she is the center of your attention, the apple of your eye. So flattery of any kind, how they dress, how they think, how they look, their style, their work, anything you can flatter them about will immediately draw a Leo to you.
Leo is also someone who loves to live life in a grand scale. So if you yourself have a built-in elegance or taste, if you dress nicely, if you appreciate art, if you go places, if you've traveled, anything that gives you an extra glamor or allure will attract a Leo. Again, keep in mind Leo has to be the center of attention. So even though you may be fabulous and wonderful and been everywhere, you must pay attention to the Leo. That is the key of attracting a Leo.
Long-term, it sounds as if a Leo then is totally overbearing. No. A Leo is deeply loving, generous, abundantly affectionate, but on the short term, flattery is the way.