When I am working on a project, it is highly likely that I would open other files from that project. In order to do that, in Helix I would do SPC F. This opens up file picker for that workspace.

I can then either navigate using arrow keys, or most likely start typing the name of the file and the file will be highlighted. As a side benefit, the file is shown on the right pane as a preview.

If I hit Enter the file will be opened in the same buffer. While I can switch between buffers using SPC b) I may want to work on both files at the same time, say for comparing the code etc.

In such cases, while the file is selected in the file picker, press Ctrl+v to open the file in a vertical split to the side 🎉

I learnt this trick via this youtube video