Hi Rob, have a look at these two tutorials/buildalongs from British Blades.
They show 2 different ways of handling a Scandi blade.....
Hidden tang tutorial Scandi Turorial The biggest mistake most folks seem to make when handling Helle & other Scandi blades, is not fitting the bolster right upto the blade & having an ugly step between the two. Don't be afraid of cutting the tang down to length either. If you're struggling to get the bolster right upto the shoulders of the blade, whip an inch or two off the tang to make your handle easier to drill.
When it comes to drilling & filing the bolster, take it slow & easy. Take the time to fit & re-fit the thing, taking off tiny amounts at a time, until it's a good snug fit upto the shoulders. If you're using a brass plate bolster, try & make it a nice smooth transition between blade & handle. Don't just leave it big!
The best advice I was given when I started was to find a knife I'd like to copy & refer back to as many pictures of it as possible at every stage of the build. Don't stop sanding/shaping until you're 100% happy that your knife matches the picture! If you do go too far, as we all have, when shaping, drilling or sanding, there's no shame in scrapping the whole thing & starting again. It's only wood! :D