in addition to the great tips above, here is one other :
You can copy text from GUI apps like the Browser etc. with ctrl+c and then
Paste it on the terminal with shift+ins keys pressed together. At times, ctrl+shift+ins also works.
Also, in the terminal itself, you can select text, by dragging the mouse ( i.e. highlight the text ) and press ctrl+ins to copy and then Paste on the terminal with shift+ins keys pressed together
Hope this helps.