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

Snapping Meshes

• Meshes Only. 
• Apply Rotation and Scale Transforms before Snapping. You don't have to but you will get some crazy results otherwise.
• Set Origin to the Bottom of the Mesh. So it snaps to surfaces. In some to most cases you will want to. You can always use the up and down arrows to adjust the depth manually.
• 'All Snapped Objects' Collection. All the snapped objects will appear in the Collection called 'All Snapped Objects'. So manage your meshes. Working on a better system.
• 'LINK' and 'COPY'. Link creates a direct link to the original reference mesh. Edit that and you edit all the snapped versions of it. Copy creates an independent copy. LINK is on by default. I found that more useful.
• Ignore Other Snapped Meshes. Use this when you don't want meshes piling up on each other. Or don't if you do!
• Number Key Shortcuts. Each Snap Mesh Slot has a corresponding shortcut number key. 1 for 1, 4 for 4 etc. 0 for 10. They will become the snapping object from then on. Esc and snap again to get back to randomization.
• Shortcuts. 'R' & 'T' rotate the snapping mesh arounf the z-axis. Up & Down Arrows adjust the depth. Left & Right adjust scale.

Target Meshes

• Meshes Only. 
  
• Turn off any Modifers in the Viewport. If you want to use Face Snap, Vertex Snap or Edge Snap. 
• Snap to Selected Mesh Only. Good for when you have a busy scene and only want to target one mesh.

General

• This is my first release of the add-on. I've tested it thoroughly. There may be a few issues.
• Please email me at ohsnap4blender@gmail.com. Please email any bugs to me!
• Read the 'Show Instructions' button in the UI. A basic 'how to'.
• Shortcut Keys. Get familiar with them. Saves time.
• Linear Array Mode. There are some issues with the raycasting over multiple meshes and over curved surfaces. Random results. I'm working on it. Best over flat surfaces.
• Using Random Depth with Linear Array. You will get misaligned snapped objects. I'm working on it.
• Undo Warning 1. Pressing Undo will delete ALL the snapped objects of your last 'snapping' session. Not individual ones.
• Undo Warning 2. Pressing Undo will also go back through any custom changes made in the UI panel. Individually. Including RESET ALL.
• RESET ALL (Shift-R). Your friend. Will reset all values including emptying the Snap Objects list. Good if you run into a bug.
• RMB & ESC. Will end the snapping session. Your settings will be saved.