Gracie Barra Bristol, (BJJ), Can Sönmez, Bristol, UK - 26/01/2012
There are three main variants of spider guard, all of which require you to grab both sleeves: this guard isn't commonly used in nogi for that reason, though it is possible to adapt. You will also normally have your feet curled around their biceps. For the most common variant, put your feet on their same side biceps, pulling their sleeves towards you, then push one leg straight, while keeping the other leg bent. This is intended to break their posture, keeping them off balance.
That is true whether or not they are standing up. There are several basic spider guard sweeps, which begin by pushing one arm out to the side, that work in either situation. You also don't have to push your feet into both biceps. There are numerous spider guard variations, such as pushing into one arm while also hooking behind their same side leg, or pushing into an arm and also holding a collar, which can set you up nicely for a triangle or omoplata.
A second option is to use your knees rather than your feet. While you could use this when they stand, it is more typical to do so when they're sat in your guard, given the obvious point that you've got a much smaller tool to work with when using your knees rather than the full length of your legs. The same sweeps can work here too, except that you're shoving their arm out to the side with your knee rather than your foot.
In nogi, you could grab around the back of their arms, just behind the elbow. In gi, you can grab the sleeves. This is something that you'll see pop up in Gracie Combatives, where it is part of the punch block series. I don't really use this one, but it's an option, and there is a bunch of stuff you can do from here: for example, the series Big Mick taught when he was visiting us.
The third option, and the one I and Dónal prefer, is known as the lasso grip. Circle your leg around the outside of their arm, so that your lower leg is on the inside, then wrap your foot so that it hooks the outside of their arm. You can then either keep your foot there, or Dónal's option of going deeper, hooking it under their armpit and around their back. That gives you a bit more control over their posture.
In terms of your sleeve grip, it's important to get that fabric as far round the front of your thigh as you can, clamping your elbow tight to your side. Braulio uses the metaphor of tying up a boat at the harbour: to pull their arm free, they have to not only fight your grip strength, but your thigh and your elbow as well.
One warning about spider guard is that it is liable to bust up your fingers. As I've mentioned a few times in the past, a black belt once told me he doesn't use spider much for that very reason. So, be careful with your grips, and know when to disengage and re-grip. Speaking of which, next time I might try adding in more about grip fighting, and possibly things like recovering spider guard from a guard pass. The technical instruction didn't take up much time: tonight's lesson was more about giving everybody plenty of opportunity to play around with the spider guard position. I may well shift things around next time, as I look to refine my lesson plans.