#1
I don't understand how to play slides tabbed with no start or end notes, like 7\ or /7.

I have seen this, when guitarists just kind of slide down the neck and just sort of off of it, without stopping at a note, and it sounds really cool, but when I try to do something like that, it's garbage. Either I'm stopping at the 1st fret which sounds wrong, or it just sounds wrong when I try to time lifting my finger off the string as I near the nut (which is my best guess for how this is done).

I'm currently trying to figure out the way you slide down toward the nut without stopping at a particular note, just sort of going off, but I think maybe there's a similar technique where you sort of slide up to a note from "nowhere in particular" -- without articulating a starting note -- and when I try to do this by just starting at the first fret and slide up as soon as the note is struck I still feel like it does not sound right, so maybe this is not how that is done either.

It's probably an easy answer, but it's hard to find anything on it online because when you search for help on slides, you get all this stuff on playing slide guitar, and or people talk about doing slides but only cover starting on one fret and going to another without talking about this other way of doing it. So I've had to resort to asking on here.

Ken
Bernie Sanders for President!
#2
For the slides that start on a note and then go down and disappear, I find that a bit of delay on your lead tone does wonders to make it sound smooth. But also, if you pull off the note at the bottom of the slide smoothly enough, muting the string right, it can still sound fine without delay. For the ascending ones that start nowhere and end at a note, I just slide right into the note from a resting/muting frethand position, and pick the string at just about any random point during the slide. With a high gain sound I sometimes don't even need to pick it, as the motion of the fast slide itself gets the string going well enough to sound a clean note when the slide stops.

Hope that helps. I have no idea if there's any particular well-known technique for doing it, that's just how I've taught myself over the years.
Guitars
Schecter Hellraiser C-1FR, C-1 Classic, Hellraiser Hybrid Solo-II, Special Edition E-1FR-S
Orange Rockerverb 50 212
Basses
Yamaha RBX374 and Washburn MB-6