Well, that’s something that doesn’t depend only on your ability to seduce your dad, but on your father’s willingness to enjoy the supreme pleasure of having sex with you, his son.
First, does your father have a close relationship with you? I think that it is easier for a son to seduce his father if they are. Though if you aren’t that close, it is just a matter of making you closer to him, isn’t? You can start asking about his day, showing interest about whatever he tells you, or you can do stuff with him, like watching movies, sitting close to him while you do it, there are lots of things you can do for your father to start noticing that you care about him and you love him. You can then start being more affectionate, smiling, hugging and kissing him more tenderly and frequently.
After thinking about that fact, you can start your approach indirectly, showing to your dad that you already are a grown man, full of boiling hormones. In other words, you have to show to your father that you are a sexually matured guy. You must make him aware of you as a sexual being. I would suggest some specific things, but try to do it only when you are alone with him:
-Sport your hardon (while wearing underwear or even your trousers) for him, in a kind of careless way, almost unwittingly but showing no embarrassment for appearing with your cock hard, erect in front of him. Play with it gently while you are showing off your manhood.
-Try to make him aware that you jerk off. It can be through some porn stuff that he can stumble upon on your bedroom when he is looking for you or something there, or it can be through your cum stained/smelling underwear that you can leave visible for him (and only for him). Along with that, try to make him hear you jerking off, moaning loudly in your bedroom or in the bathroom. After that, you can make him catch you jerking off: you can make him come to talk to you in your bedroom “by accident” (of course, you will make sure that he will go there without him knowing that you already know that) so he can catch you completely nude, with a full hardon or even better, masturbating. I would suggest you make him catch you nude with a fully erect cock first, so you can talk to him as if nothing is happening and force him to talk to you while you are fully naked with your cock hard. Try to act a little surprised, as if you were embarrassed, but that must not endure more then some seconds, then you just don’t try to hide your hard cock, as if you forgot that because you’re paying attention to what he is asking or telling you. In other words, you must behave like if that’s something natural (and it is, really). After that you can make him catch you actually jerking off. Then try to act a bit embarrassed, but not completely. I would suggest you to stop masturbating when he catches you “by surprise”, then resume your job, just more slowly, as soon as the “surprise” is gone. To make him not aware that you’ve been caught completely “by accident” you can leave some music loud as if you were listening to it and you didn’t notice him coming while you were, with your hardon, ready to jerk off or already doing it, if you are already on this phase of your seducing game.
-Talk about sex with him. It not necessarily must be about sex (you know, you can kinda lure him think you like girls and talk about that, but I don’t know if that is necessarily effective for you to get him on your game), you can just talk about, you know, cock. You can play the innocent son that is not sure about his own cock, and tell him you think yours is a bit small or something similar, like the foreskin (if having or not is not a problem, if it will affect your “joy” with it). Try to start the conversation and then suddenly you can make your cock hard during the conversation (I think that won’t be difficult, will it? I know you will be always somewhat nervous while you play these games but I’m sure you will be pretty much turned on too). Then you can turn the conversation to him, asking if his cock is the same size or anything like that. While you are doing that (and everything else I have already suggested), try to notice if he himself is sporting a hardon. You can do it discreetly at first, but during this “cock conversations” I think you can do it more ostensively, for him to really be aware that you are looking to his cock. Now, it depends on how the conversation goes (and everything else goes) but you can then jump to sexual stuff more directly, and always turning the conversation to him: tell him how much you masturbate, and if he did or does it yet (and how much), if he cums a lot, if his sperm is thick, if he has tasted it and how it tastes and so on. You can ask these things on this conversation or during others you start with him about these “cock issues”, that is up to you. During all these talks with him about cock stuff its up to you to notice if you can ask him to show his cock to you and if you can touch it, so you can compare with everything you told about your cock to him, you can even ask him to jerk off in front of you or with you, so you can solve your doubts…and then, hopefully, things will start to happen!