Don’t think in terms of casting spells on other people. This is bad. (See: Alex Sumner’s answer to Why are love spells considered white magic?)
Instead, think in terms of casting a love spell on yourself – i.e. to transform yourself into the kind of person who can attract true love. Mind, though, you have to really transform. If a new lover enters your life and you haven’t changed in any way, you will still have the same luck that you’ve always had, so he will walk straight out again.
A simple spell might be to perform the Middle Pillar Ritual, and then breath bright Green light into your aura, so that is shines like an Emerald, whilst vibrating (i.e. chanting) “Yod Heh Vav Heh Tzabaoth.” (Emeralds and the colour green are traditionally associated with Venus, whilst the words chanted are the Divine Name associated with Venus in the Qabalah.)