what are some tips for determining the sex? I love looking at goats but know next to nothing about them. 
There are a lot of different ways to determine the sex of the goat. I have been able to see a goat's "male package" from behind a time or to, but most of the time that is not the easiest view to get of a goat. The horns are usually the best way to tell the difference. A male's horns have MUCH more mass than a female's. Additionally, a male's horns will make almost a quarter circle as opposed to a female's which will start out very straight and then kind of hook right at the very end.
In the first picture below you can see that this one is obviously a female. It's body size gives it away as bigger than a yearling goat but the horns have almost no mass at all and are very short.
Similarly, the second goat (with the young kid) is also a female (a good way to tell is if it has a kid with it, although in a big herd the kids will really mill around quite a bit and sometimes you can't tell which goat a particular kid belongs to). One way to tell this is a nanny is the long straight horn at the bottom, and very little mass. A good rule of thumb is that if the base of the horn is wider than the eyeball it is usually a male. In this case, the horn is obviously thinner than the eyeball. You may also notice that the horns seem to be particularly long. That is partially due to the lack of mass that makes them look very long, although the longest horns ever measured on goats are all on nannies. In general, a billy's horns will be longer than a majority of the nanny's.
In the third though sixth pictures you can really get an idea of the straight horns that hook right at the end and the lack of mass. Almost all of these nanny's have particularly long horns for a nanny. I am convinced that the Mt. Baker herd generally has longer horned nanny's than most areas and I actually believe I have seen a few that might push B&C. The last picture is of one such nanny that really seems to have it all. It is quite massive at the bases and very good length and a very wide spread. Most people don't realize that spread can make a big difference in goat scoring and a big nanny like this with a particularly wide spread could just push the B&C boundary.
