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Asides from the traditional or superstitious beliefs surrounding gayuma and love potions, spells and magic, there are certainly a number of ways to try to improve the chances of a person falling in love with you. I personally believe that gayuma is not a matter of magic or of special ingredients, but it is a matter of giving a person a happiness that they cannot find elsewhere and/or making sure that they think of you when you are not around and that they miss you, need you or crave you somehow.
A sense of humour or a sense of 'fun' is a very important attribute in an effective gayuma. Of course, if a person is happy in your company, when you are not there, they will miss that feeling of joy and happiness.
There are ways to encourage a person to think about you more often. One such way is to introduce habits or markers. Do you know how it feels when you have broken up with somebody and even years later, you still feel a presence of that person when you hear your "song" or walk past that place you used to eat together or even hear particular words or phrases that you first learned from that person. Well, creating little markers or thoughts can trigger a person to think of you next time they see that marker, and this can be a very effective way to stay in that person's mind or thoughts.
I do not believe in the silly mind games that people play, where they say "be hard to get" or something similar. But, it is true that people are more likely to value something dearly that they feel they have had to work hard to achieve or obtain. I think that relationships are the same in that both sides of the relationship should have to work at it and keep putting effort to make it really work well. I think it is important to allow each other to put efforts to show each other that you are interested, and should certainly not be one-way-traffic. If it is getting to be one-way traffic then there can be no real value in that, let the magic come from the efforts to win each other so that that investment of effort is valued and something that both parties will not want to lose.
It sounds obvious to some, offensive to others. Intimacy that feels very amazing (not necessarily hard and aggressive, but just amazing to that person) and unique is something that as animals we do not want to lose. That once-in-a-lifetime experience can be like a drug and is possibly the most effective form of gayuma.
There are many tricks and magical spells and various methods of encouraging a person to feel that they are in love with you, but really, being true to yourself and true to others is the only real way to find true love that lasts. The tricks are great, but are only tools to help things along a little. If there is no real connection there, well, maybe it is better to find a more appropraite partner.