This isn't definitive, but I haven't seen the following in many of the books I've read; maybe they'll be helpful.
Necklaces tend to fail at the clasps–that is, at the ends. Cut the stringing material as little as possible. I often carried this extremes, looping one piece of tigertail or beadalon back and forth between the ends of a multi-strand necklace.
The stringing material should comfortably fill the smallest sized hole of the beads being strung. This is particularly important if you're going to be knotting, since otherwise, your knots will disappear into the holes. If you're going to be passing the stringing material through a bead more than once, pick one with a big hole. The weight of the beads relative to the diameter and strength of the stringing material is much greater for bead stringing than bead weaving; choosing a thread that will often pass through a hole 3–4 times, as peyote stitchers do, is asking for trouble–unless you do in fact pass it the four times.
Use good quality stringing material. If you're going to use thread, use good quality silk or nylon—for example, I've found that Gudebrod rod-winding is substantially stronger than ordinary carpet thread, even though both appear to be the same, pure nylon. I like their silk, too. E and FF (doubled) are good weights for pearls/small stone(4mm) beads and larger (6–12mm) respectively. Avoid stringing austrian crystal or mandrel wound glass beads on thread. Use cable or memory wire instead.
My favorite is the new 49-stranded nylon sheathed cable, which goes under brand names such beadalon and softflex. I prefer cable for a number of reasons: it's stronger not least because resists fraying much more effectively; it stretches imperceptably; it's faster and easier to string–no needles to get lost. I find using seed beads as spacers far easier and more flexible than knotting for contrast: with thread you're pretty much stuck with the same color and size knot for the length of the piece, but seed beads can change every bead, if desired. Just about the only real advantage of thread is if you want to actively incorporate fabric by way of knots (macrame), weaving (tapestry needleweaving) or the like. Monofilament is good for laying out designs and not much else.
Beads don't always have cylindrical holes—often they come cone or dumbell shaped. When stringing beads with temperamental holes (i.e. drilled in India) always string from the largest side down to the smallest. Wax silk or nylon. Cut 7-49 strand cable on an angle with sharp cutters. Beads with what I call spindle or dumbbell shaped holes are the worst.
Doublestringing. Sometimes you have a bead with a substantially larger hole than the rest. To center the stringing material inside the bead, string small beads (seed beads, liquid silver, bullion) that are just smaller than the bigholed bead's hole; then the bead will lay properly. If you large holed bead is transparent, choose attractive beads to go inside. Liquid silver or gold will imitate the look of wire. In the case of spindle shaped holes, you can plug the cone shaped ends with small beads that just fit.
In the case of silk, double stringing can also be used to protect your fiber from beads with sharp metal holes. “Dynamites”, those really tiny liquid silver beads will go over .018 beadalon, and inside of regular liquid silver, most metal beads, 4 and sometimes even 3mm austrian crystal. However, these tiny tubes have a nasty tendency to temporarily split if shoved onto silk that is slightly too thick, resulting in the thread bearding outside of the dynamite. This isn't good, because then the dynamite gets stuck. Test ahead of time on a scrap piece of thread, instead of a necklace you've already put 5 hours into.
You can check the drilling of any kind of beads by grasping the strand in both hands and forcing the beads tightly against each other. If some pop up or down, the strand is probably badly drilled. (This works for hanked seed beads, too.) Stars, with those holes coming out of the points, should be particularly carefully checked. If the beads are on a very thin thread or wire, the holes are probably small. Be especially with careful with turquoise, in which the holes may be filled with wax; though as a rule small holed beads are your transparents—quartzes and beryls and the like—turquoise is often an exception to the rule that opaque (taiwanese) beads are usually decently drilled. Beads cut and polished in India—garnets, tourmaline, smokey quartz, labadorite, citrine, amethyst, peridot, topaz/aquamarine—will usually have smaller and less regular holes.
Moreover, don't just assume all beads are created equal. I've seen some dismally made black onyx beads (all black onyx is dyed, by the way, just as I gather all hematite is actually synthetic) that upon closer inspection were sort of squarish. I usually get caught at this during G&LW show frenzy. Take the time to look before you buy; a jeweler's 10x loupe can be very helpful. Remembering to take the time to use the loupe is even more so.
An awful lot of stringing is incredibly boring. Strung beads respond to the same attention to detail any other art form does. Most stringers start with color, or perhaps an accent piece. Beads can be thought of as having hue (color), surface finish (shiny, matte, pearlescent, etc), transparency/translucency/opacity, and shape.
You will want any given set of beads to have some qualities in common and other contrasting; for example, if you're going to mix highly polished, vividly colored austrian crystal with matte or even shiny opaque stone, then you probably want the color, and perhaps the intensity, and perhaps the hue of the beads to match (as, for example, malachite and kelly green crystal.) Some beads have so few qualities in common—vivid fuscia austrian crystal and any of the tertiary brown, opaque jaspers, for example, that combining them can be a real challange.
If that sort of challange appeals, then you need to bridge, from one kind of bead to another. The comments about the pink rhodonite flower necklace give an example of this sort of thinking. Essentially, you want beads that share some qualities with the disparate ones. So if you have a transparent brown bead (smokey quartz) and an opaque green (rhyolite) one, then maybe you'd like a transition that is transparent and green (peridot, greenish-bronze glass). Or perhaps translucent with brown and green (serpentine).
Finally, most artwork prospers from what a friend of mine calls poison: a little bit of something that's different to give some zing. Emphasis, please note, on the little. A bit of orange (carnelian, say) or crimson (garnet) for the example above, might be nice.
Now for shape and size: I tend to think in patterns, and the process, for me, is somewhat fractal: I start out with small units of just two or three beads, that relate well to each other, then build up. These might be small beads—liquid silver, 2, 2-1/2, 3MM, 4x1MM disks—which I'd then set against a slightly larger bead, which in turn becomes part of a unit of large beads, say 8–12MM. Quite often the patterns have a bit of a logarithmic quality to them: say, 2mm,3-3mm,4x1 disk,4x13,6mm,8mm disk, 10mm, 8mm, 8x12 teardrop, 3mm, 2mm. Note the amount of length in the small sizes going to the larger: also that the design contracts faster than it gets bigger; this sort of asymmetry keeps things from getting too predictable. Sometimes half a mm can make a difference; this sensitivity to proportion is what I tend to see ignored the most. Folks see something that's smaller than something else and let it make do; and this results in clunky, bumpy design. If it needs a 3mm silver, don't just shove a 4mm in because that's all you have.
If you have some cool shapes, use them sparingly! Or, string a stretch of them altogether, so they work as a single overall unit. The big thing is to make certain they're incorporated into the design. Beadstringing is fun because by balancing individual beads with the overall necklace design you can both showcase attractive beads and make a cohesive whole, something you can't do if you make a bag out of delicas or simply string 20 expensive artglass beads on a cord.
And finally, an effective, though not necessarily quick, way to make chips look good: sort by size and shape (and color if need be), orient them all the same way (if for example one side tends to be flat and the other rounded) and space with a seed bead. Discard (or save for beaded wirewrapping) all badly drilled ones. I think a contrasting or analogous, rather than matching color, of seed bead works best.
These are just a few of the things I've discovered; the biggest thing to keep in mind is that all rules are made to be broken, and if you screw up stringing, so what? It's not like you've irretrievably ruined a $10 or $20 sheet of 300# watercolor paper. Cut the damn thing apart and try again! You've lost nothing but your time, and gained great experience. Have fun, play.
Unless otherwise noted, text, image and objects depicted therein copyright 1996--present sylvus tarn.Sylvus Tarn