I weigh myself twice a day and I consider that restraint

! Once in the morning and once right before I go to bed (so that I have an idea of what my weight will be in the morning and there aren't any unpleasant surprises

).
Once in a while, I'll also weigh myself after working out, but usually only if I've worked out in the morning and haven't eaten yet. I weigh myself then because that is usually my lowest weight and it's nice to see that low number on the scale (even lower if I sat in the sauna for a bit after working out and I've showered and dried my hair).
I use a $30 Homedics digital scale. It seems pretty accurate; it agrees with both the scales at my gym and my doctor's office. It does round my weight to the nearest .5 lb, but that's been fine for me. If you are in the market for a scale, definitely spring for a digital one.