Tips for getting the best out of the Oh Snap!:

Snapping Meshes

• Meshes only. Snap Mesh slots only accept mesh objects.
• Apply Rotation and Scale transforms before snapping. You don't have to, but you'll get much more predictable results if you do, an un-applied transform on your source mesh can throw off scale and rotation on every copy placed from it.
• Origin placement matters less than it used to. Setting the origin to the base of the mesh is no longer something you need to do manually. Auto Base Offset is now on by default and handles this automatically: it measures the object's own lowest point and uses that to sit it on the surface, regardless of where the origin actually is. You can still put the origin at the base yourself if you prefer full manual control, or turn Auto Base Offset off in the panel if you'd rather do it that way, but for most people, it's one less thing to think about now. The Up/Down arrows are still there for fine manual depth adjustment either way.
• The "0h Snap! Snapped Objects" Collection. All snapped objects are filed into a collection called "0h Snap! Snapped Objects" (yes, with a zero — deliberate, so it sorts to the top of your Scene Collection). Every batch whether from a single click, an Array, Scatter, or Curve Array gets its own timestamped sub-collection inside it, so it's easy to see what was placed and when. There's also a "Delete Previous Snapped Objects" button that removes the most recent batch and works across every placement mode, which you can press repeatedly to walk back through your history.
• Link and Copy. Link creates a direct link to the original reference mesh; edit that, and you edit every snapped copy of it. Copy creates a fully independent copy. Copy is on by default; safer for most workflows, since editing your original source mesh later won't retroactively change everything you've already placed. Switch to Link if you specifically want that shared-editing behavior.
• Ignore Other Snapped Objects. Turn this on when you don't want new objects landing on top of ones you've already placed. Leave it off if you don't mind, or want that behavior.
• Number key shortcuts. Each Snap Mesh slot has a matching number key; 1 for slot 1, 4 for slot 4, and so on, 0 for slot 10. Pressing one locks that slot in as the object being placed. Press the same number again to go back to random no need to exit and re-enter the tool.
• Shortcuts, worth knowing well. R and T rotate the current object around the Z-axis. Up/Down arrows adjust depth. Left/Right arrows adjust scale. Also worth knowing: Z/X/Y toggle random rotation per axis, S toggles random scale, D toggles random depth, and J toggles random surface jitter — all quick on/off switches while you work.

Target Meshes

• Meshes only. The surface you're snapping onto needs to be a mesh object.
• Turn off viewport modifiers if you want precise Face, Vertex, or Edge snap. Snapping targets the mesh's evaluated (modified) geometry, so a Subdivision Surface or similar modifier can shift exactly where a "vertex" or "edge" appears to be relative to your base mesh.
• Snap to Selected Mesh(es) Only. Good for busy scenes where you only want to target specific meshes, this now supports selecting more than one mesh at once, not just a single target.

General

• This tool has had a lot of iteration since the first release. Several of the original release's rough edges; random Linear Array results on curved surfaces, misalignment with Random Depth, embedded-looking objects have since been fixed or superseded by newer features (Conform to Surface, Auto Base Offset, and a more stable placement/orientation system). If you hit something that doesn't look right, it's worth checking the User Guide first there's a good chance it's a setting rather than a bug.
• Bugs and feedback:message through the Superhive product page.
• Read "Show Instructions" in the panel. Still the fastest way to get a quick reference without leaving Blender.
• Get familiar with the shortcuts. Genuinely saves time once they're second nature; see the Full Keyboard Shortcut Reference in the User Guide for the complete list.
• Conform to Surface (Linear & Radial Array). If you're placing across a curved or bumpy surface, turn this on; it projects each point onto the actual surface underneath (occlusion-aware, so it won't fall through to hidden geometry below), instead of following a straight line or flat circle between your click points.
• Backspace and Shift+Backspace are two different things. Backspace undoes just the last individual object you placed. Shift+Backspace deletes everything placed during the current running session. They're intentionally separate, so a quick correction doesn't have to cost you the whole session.
• Blender's own Ctrl+Z undo is separate from the above, and will step back through your panel changes too, including a Reset All; that's normal Blender behavior for any addon's properties, not specific to Oh Snap!.
• Reset All (Shift+R). Still your friend; resets every setting, including clearing the Snap Mesh slots, back to defaults. Good first move if something's behaving strangely.
• RMB / Esc ends the current session. Your panel settings are kept as they were. In the standalone tools (Scatter's Set Clump Point, Curve Array), RMB/Esc cancels the current action without placing anything if nothing's been placed yet in that pass.