[Crex]

Just an extra note - Use old manilla folders or cereal box panels to make you a pattern of your sheath before cutting up leather. Remember to be a bit liberal with the outside edges so you have a little room for truing up your edges. If making simple pouch style sheaths, remember that paper is much thinner than the leather so allow even more with these. The pattern will allow you to plot or arrange your leather cuts with the least amount of waste and avoid any unsightly blemishes in the leather's surface.

I usually trace the pattern on the flesh side so mis-marks don't show (it will happen). I learned from Chuck many many moons ago to use a red pen or orange sharpie to draw on leather. Most stains will shade out the marks and they disappear.

Always keep you leather working area as clean as possible and wash your hands well before starting. Damp leather will suck up every bit of dirt, oil and grime. You won't be able to get it off and will wind up using a lot of the darker dyes to cover up the finger prints, smudges, etc.

Finishes are a whole nuther animal. You'll have to find what works for you. Neat-Lac is glossy and makes leather look "plastic" (to me). I use a lot of Bag Kote - neutral/satin painting it on then wiping off excess (this takes practice to eliminate streaks). I also use a beeswax/neatsfoot oil mix for that oil soaked look - make sure the neatsfoot is the real thing, lot of fake stuff on the market.
There are a lot of finishes and techniques out there and everyone has their favorite. You will have to weed through them to find what does what you want and suits you.
Keep in mind that most finishes will darken the leather considerably, so test scrap first.