Forward Shoulder Adjustment - I'm both a sloucher and have done a lot of computer work in the past, both reasons for forward shoulders. My standard adjustment is 1/2".
Add 1/2" to the outer edge of the shoulder seam on the back yoke. Since the sleeve head is not on the seam line make sure to also move the sleeve head notch 1/2" forward as well.
Adding a dart with out an FBA - Sometimes you need a dart but not extra width in the garment. No worries you can just draw a dart in. For a semi fitted look I've found what works best for me is a dart about 4" down from the armhole angled up to the bust apex.
First I mark the bust apex which I've found through a lot of trail and error on other patterns. If you have no idea where your bust apex is, holding the pattern piece up to your body is a good way to start. (My breast tissue is very heavy so my apex is usually way below where the big 4 mark it.) Draw a line from the bust apex to the side seam right around where you want the dart.
You'll need the proper shape for the dart intake so add some more paper to the side seam, fold the dart like you would when you're sewing it and then cut the paper straight along the side seam. When you open the dart back up it will have the correct angle on the edge. (Sorry about the multiple dart, had to move that sucker up)
Wide Upper Back - My upper back is a bit wide through the arm scye so I always add a 1/2" extra ease for free arm movement. Usually I slash through both the yoke and the back shirt and put a small dart in the back shoulder seam. However Archer has a wrap around yoke and a dart would look very strange coming over the shoulder to the front. Fortunately compared with my shirt block, Archer had about the right amount of width in the yoke. So today I'm only going to be enlarging the main back piece.
First a slashing line was drawn on the back - measures in 2 1/2" from armhole edge on the yoke seam and 1 1/4" down from the armhole seam.
Sway Back - Lots of extra fabric at your center back that pools up when the hem of your shirt hits your butt? I got that in spades. My usual sway back alteration is to pinch out 1".
The lengthen/shorten line is usually a good place to put the sway back alteration. I put mine right above it. Mark out the amount of fabric you want to remove, (in my case 1") pleat the pattern so that you take out the full amount at CB but none at the side seam. Tape that sucker down and you're done.