Dont worry about slap. You dont need to. OK, maybe one technique, the octave thumb/pluck, you thumb the root, and pluck the octave. That's all you need as far as slap goes, fr now.
A few local drummer call me incredibly funky, I'm not sure I am, and I thinks its my white nazi-ness that freaks them out and makes them say this. ( I cant help my genes and baldness), but here's my "secret":
Funks in the spaces man, NOT on the 1/2/3/4 beats. Dig?
E.G. I have a habit of coming in on the "4 and" instead of the 1. I'll hit the "root" time on one, but 'burp' into it. I respect rests or "air" BIG time.
Anthony Wellington is working on something that will help a ton, but for now, you MUST practice your off time, i.e, playing notes NOT on the 1-2-3-4 beats but on the "e" and "ands" as in 1-e-and-2-e-and, etc..... do this and you WILL feel Da Funk. I dont mean missing the "one beat" unless it is musically correct to do so. I mean getting you comfortable with timing that is NOT 1-2-3-4 common time. That is not funky atall.
As a bass player, YOU set the pulse of the song. Remember, you are the "glue" between the percussion and melody of the tune, so you dictate the entire feel of the song. This is what I pay VERY strict attention to. Pulse.
Be cautious: as my funkability has grown , so has my lack of interest in certain genres of music that are simply too "white" for lack of a better word. This is not racism or jingosim here, I beleive it to be the natural progession of funkability, as I grew up exposed to only Euro style beats and rhythms.
There was a series of threads entitled Funk 101 or something, where folks would post good examples of funk, with emphasis on bass. If those links still work, you're golden. If not, and if you send me a digital device, I'll put all those on the device for you. As the TB community has helped me grow, we shall you.
Lastly, a good last minute Xmas present from your mom or dad would be " Standing in the shadows of Motown", by Dr Licks. . This is all about James Jamerson, and you'll get an audio CD. Its pre funk, to be sure, but man, you simply HAVE TO be exposed to James and try and copy his lines, his feel.
if you feel the need to learn slap ( which , your timing is the most ciritcal thing right now, imho), please consider Ant Wellington's online slap courses at Link Removed Much slap is done wrong, in fact most I see. I encourage you to learn it right, from the masters.