What I have learned about Inkscape

Always remember that the computer sees things you don't - eg. the vector lines under a fill or picture.

If the file is huge and has lots and lots and lots of nodes, exporting it to pdf can be a hassle.

Sometimes when things aren't working for some mysterious reason, ungrouping objects and/or breaking the paths apart fixes things.

When importing Adobe Illustrator files, you should check if automatic scaling is on. Other things might mess everything up also, try not to mix Illustrator and Inkscape at all if it's preventable.