What's your plan in case of an alien invasion???
I would probably start by getting my family and friends safe in an underground base. Then start gathering supplies and weapons to start a rebellion. Then get people to fight against the aliens or die trying.
If they are capable of galactic conquest then I fear that we are far to primitive to even dream of repelling an alien invasion. That being said, i'd still try to survived as long as I can and take out as many of these alien as I can if possible!