This Youtube video gives a good walkthrough of how to draft a simple pattern. Below I have noted some of my most common issues in the Valentina/Seamly 2D software:

Selecting nodes for Details

Nodes are important for certain functions like seam allowance. In order to be able to use nodes in Details mode, you must select them in Draw mode. This means taking careful consideration to select each point in between lines and curves, not just selecting the lines and curves themselves. If somehow you miss a point, it can’t be added; you will have to redraw the outline.

Seam allowance on fold

Keep in mind that Valentina always works clockwise.

1. Determine the nodes involved.
2. For the node on the lower end of counter clockwise, change seam allowance to zero for after. For the node on the upper end of counter clockwise, change seam allowance to zero for before.

Troubleshooting seam allowances

I have come across a few odd things when trying to do seam allowances. These are the solutions I came up with:

• If seam allowance on corner intersecting a curve cuts into pattern, make sure the curve is not somehow twisted. It may not be detectable until the seam allowance comes out looking strange.

Passmarks

These can be useful for larger patterns, or for more detailed patterns as required with bra-making.

• To create a passmark, there must be a point made in Draw mode. For size-alterable pieces like a bodice that needs to match-up with another pattern piece, use a formula to place on pattern (ex. halfway between two lines)
• Use an appropriate mark for what you are doing (ex. using a different mark for a bust point vs. a side seam)
• Passmarks must be listed between the two points on the pattern otherwise pattern will be distorted
• Mark as a passmark in the list so it is not seen as a regular point on the pattern