I've explained a few methods for making your own patterns. In graphing tessellations we did tessellated bead patterns, and in snowflake patterns we explored kaleidescope type patterns made in 6 sections in peyote. Using BeadTool is one of the best methods for making patterns from photographs, and the program is really nice.

But people ask me how I do most of my graphing. If it's a photo, I use BeadTool. For the simple patterns that I do most often though, old fashioned graph paper. I use it on my computer now in layers in a graphics program, but I used to print it on thin paper and use pencils.
One of the best things about graphing your own patterns is the flexibility with stitches. If you can find or make a graph for whatever bead count you want, you can graph it. For my example, I used 2 drop peyote because it handles curves wonderfully and this picture I drew of a rubber duck.

If you use pencils, you'll want to work on a transparency or on thin paper with the graph paper over the image you're graphing. Vellum works great. If you use a graphics program, work in layers. I turn the transparency down on the graph and lay it over the image usually.

So first you'll outline the image, lightly marking the paper if you're using paper. This is just basically setting up the shape. You want light marks so you can erase and reshape it.

Color in your outline and do the rest of the design the same way, you may want to make some adjustments as you go, so if you're using pencils, work lightly.

See that? I'm not really happy with the eye, and I think the back end of the duck needs to curve out just a little more. So I make some adjustments. Moving and re-shaping the eye, and adding one more line of beads to the back end.

That looks pretty good, but I still need a background. The duck on it's own is cute, but not really ready to be an amulet bag.

You can get the full bag pattern here. It has the duck on one side, and just the plain background on the other side. It's 32x32 beads.
You can download blank 2 drop peyote graph paper for amulet bags in 32x32 beads here. This will make a smallish amulet bag. I love the smaller ones on fairly short straps so they fall an inch or two under my collar bone.
There is a lot of free beading graph paper here in a lot of stitches.