How can I hang Christmas lights inside?

Hi try some Command hooks they come in different sizes and are easy to remove. .I use them a lot. .

Thumb tacks show the least. Get the clear plastic long ones in an office supply store. You can tack them to the window frame or use tiny Command hooks if you have vinyl. Walmart carries a large assortment.

Veronica...I was thinking about the command strips and hooks...can get clear ones too!

Command hooks come in many sizes,clear or white,lrg-small,easily applied & removed

To what surface do you wish to hang lights (drywall, textured plaster, tile, wood, etc.)?

Command hooks are a great way to hang things temporarily without damaging your wall.

Depending on the weight, if hooks aren't sufficient try the cord bunders:

https://www.command.com/3M/en_US/command/products/~/Command-Cord-Bundlers/?N=5924736+3294529207+3294780016&preselect=8719411+3293786499&rt=rud

Depending on where you want to hang the lights, zip ties may be an option. They are cheap, easy to use and are sturdy. I have seen green zip ties sold as 'wreath ties' in fancy packages (see example first picture). It is more cost effective to use plain zip ties sold at the dollar store (second picture).