How I make tapestries, including how to do the horizontal stitch, a stitch I believe I invented myself :] These methods are advanced, and require knowledge on; masks, odd peyote stitch, even peyote stitch.
Step 1
To start, figure out where you want to start. There are two main options; at the top/bottom, or at the widest point. I prefer to start at the widest point, so I don't have to add on as much. However, I find the top/bottom method to be simpler, since you only have to focus on going in one direction, for the most part.
Step 2
First step of the horizontal stitch. First, start at the bead above, or below, the first bead that touches the part you want to add on, if you have one. Tie your string here. Then, following the arrows above, weave your string through into the bead below/above it, making sure it is facing away from the base and towards where you want to add.
Step 3
Next, add on a new bead, then weave back into the base bead you just came out of. Like before, weave down one bead, then into the bead you just added. Then repeat steps 1 and 2, adding a new bead, weaving back into the base, etc.
Step 4
To start a new column, simply finish steps 1 and 2 like normal. Following the blue arrows, make sure your string is coming out of the bead you just added, the final bead in this column. Weave your string into the base bead you just came out of withOUT adding a bead, then weave UP and out of the final bead, following the cyan arrows. Then continue like normal, adding a bead and so on.
Step 5
To tie off, simply repeat the first portion of step 3, weaving down into the base without adding a bead. Tie your string off here.
Step 6
Next, we figure out how to add vertically. As an example, in our example Two 'n' Crew pattern, Two's left leg needed to be made after the base. There are a few ways to do this. The main, and obvious one, is to simply tie on string and work your way down like usual. However, it's important to note that, if the number of columns is odd, you need to start at a particular side to avoid having to do the odd peyote method on both sides. Make sure the side you are tying your string on starts with a dip, rather than an exclave.
Step 7
The next option is the stick method, where you add on a column, or stick, of beads. You simply add on a bead, then loop back into the base bead as shown in the red arrow. Weave back into the new bead, then down, and add another new bead. Weave back into the first bead you added, then down into the next new bead, continuing as such until you reach the end. After this, you build off using the horizontal stitch. This is best used if you are building a thin piece in between two wide pieces. Do note that you may end up on the wrong side, and the only way I know to fix this is to simply tie off your string and retie it on the correct side.
Step 8
The final method is to simply make the two pieces separately, then tie them together. I used this method on my Rambley tapestry, specifically his tail, since I knew it would waste a lot more time and string using the horizontal stitch.
Step 9
Finally, diagonal pieces. This is incredibly simple. You simply weave the string out of the base piece, weave on your new, bead, then go up back into the outer portion of the base bead. I recommend doing this twice. Do note that diagonal pieces are a little finicky, and may require adjusting.
And that's it! Congratulations, you made your first complex tapestry, congrats! Hope this helped, and allowed you to make more complex patterns. Go ahead and share this with people, no need to credit me unless you use this or any of my other tutorials directly.