A little help figuring out electronic switching

[9Lives]

So lately I've been obsessed with understand the basics of fet switching, I just have a hard time putting all this info to use. I've read a true buttload of info online (all the articles by RG, premier guitar and some of merlinb's projects). For some reason I just have a hard time sorting all of this out and applying it. Basically I under stand you need a bias to the drain and source and apply 9v to the gate through a diode and you have a basic working switch. By grounding the gate it turns it off. What I have trouble with is where to insert capacitors and why.

What I'm basically trying to do is use a simple Jfet stage booster, or a mu amp, or even a mosfet boost and apply jfet switching to select between the amplifier and the source follower buffer. What seems to be happening it when I ground one jfet  they are still both bleeding together. After sitting here writing this I'm thinking I need a capacitor between the source and the switching fet but this is just my thought.

Anyone whos got this method under control, I'd really appreciate some guidance. Like I said, I've read most the articles if not all that's searchable on google and the forums. I just can't seem to apply it.   Thanks.