My experience with fencing deer out is that the larger the enclosed area, the better fence you need. They don't seem to want to jump into a small enclosed area very much. You can get by with a pretty cheesy fence around a small garden. Your mileage may vary depending on the deer population and available food for them. Another thing to consider is if they do get into your fenced area, they will panic to get out. This can wreak havoc with your garden and your fence. We will sometimes get deer or fawns in our vegetable garden and they will blow through our fairly stout fence, even if we open both gates. I've never tried the fishing line thing.
