Its my habit to separate those images from the bulk of pictures taken from digital camera, which I would like to upload to my flickr account. I normally copy these images to a specific folder called pics to upload placed on my desktop in windows.
Folder monitr is a free program which allows you to upload your photos to the flickr account from a folder, it will watch the folder once you configured and then automatically upload the new images you copy into that folder.
Related Flickr Tip - Automatically Upload and Sync The Photos On Your Flickr Account
You will need to authenticate it to before it starts to upload to flickr, we would recommend to add this program to windows startup so that it keep running in the background and automatically upload the photos you copy in a folder monitored by this program.