I use little but fluorocarbon for hooklinks. I also use spade end hooks. They are tied with a Drennan hook tier, so whatever knot it is that it produces. At the other end, I use a figure of eight loop knot.
The few times I've tried fluorocarbon for hooklengths I haven't particularly taken to it, and I've been happy enough with the brands of mono I use. That said, I wouldn't want to be missing out on any big advantages fluorocarbon might bring. I'd be interested to hear what attracts users to it and what particular strengths it has in their experience.
Half blood for eyed hooks and swivels and snell for spade end hooks. Haven't found anything to be significantly better than the half blood for the Drennan Supplex fluorocarbon.
nottskev: I find it's less likely to spin up and it's much easier IME to smooth out any kinks. Whether it catches more fish or not I wouldn't know. It is quite stiff which intuitively might put fish off but I can't say I've detected any difference. It's one of the reasons I experimented with sewing thread which is super soft but haven't really been in a situation where I could AB it due to the C19 restrictions. Next time I get on the canal I will.
I'll just add that FC doesn't seem to suffer at all from having shot pinched on. I've never had it break where the shot has been. Not that I'm recommending it but it doesn't seem to matter how hard you pinch the shot on either. Not for the gauges I use, 2 and 3.3lb.
A matchmen hook tier with figure eight to attach to mainline, I only use loops for method hooklinks.
For tying swivels, I use a tucked blood knot, figure eight knots for nearly everything else I tie. Everything used to be loop to loop but I've changed back to how I used to tie.
On advice of my feeder fishing mentor in belgium, i made my hooklinks with relatively strong fluoro (0.30). It's not for discretion, it's because for big bream and barbel a long hooklink helps, and fluoro tangles less. Knots we use there is the palomar, simple and super strong.
I haven’t used the blood knot (tucked or otherwise) for at least 25 years now because I’m not that enthralled with tying strangle knots which can sometimes weaken the line at the knot usually when a lunker is hooked. Plus I don’t like the way the line points outwards from the hook eye.
For the past 25 years or more I’ve used the 4 or 5 turn Grinner knot (or uni knot) both for the hook and for my swivels, I also use the figure of eight knot for tying loops, and I use the ‘knotless knot’ whenever I tie a hair rig.
If I’m using fluorocarbon then I sometimes use the Palomar knot but if the hooks eye is a little too small to have two pieces of line through it then I’ll just use the Grinner knot and I’ve not had any problems with it yet.
A bit after the event I know but the two knots I use are the standard spade end knot (form a loop down the shank, six turns and back through the loop) or for eyed hooks a half blood knot, not tucked.
I've also used it with a knotless knot many times without any problems.
I've used flouro a lot over recent years, the two main reasons being water clarity due to its alleged invisibility and rocky waters, particularly the nearside of many a Trent swim where I find it much more resistant to abrasion than mono.
The downside is it's thicker than its mono b/s equivalent but that's not an issue (after all it's supposed to be invisible with a low light refraction index) unless suppleness is required as it's also a bit more rigid.
I've toyed with this stiffness in certain trotting situations, particularly where i'm holding back, and think it could work in my favour but I'm getting down to the real nitty gritty of particular swims and flow strength.