Some of the many things I've learned from this series:
1. Aliens can travel and communicate across universes, cloak their ships, hack the most advanced computer and/or radar systems but they are completely unable to break the signals of regular mobile phones.
2. If you are a member of a small resistance unit that is fighting an interstellar alien invasion it's perfectly fine to use cell phones to communicate - furthermore there's no reason to use any type of code or aliases when talking on the phone as you (per #1 above) can be safe in the knowledge that no-one but your team can listen in.
3. If you are a member of a small resistance unit that is fighting an interstellar alien invasion you need a club house: preferably something that resembles the Bat Cave or a dungeon. The cellar of a church is perfect since getting an internet hook-up will not be any problem and your comings and goings won't be noticed by any non-guerrillas. If the club house can be located at the workplace of one of the unit's members this is even better as it will cut down on time spent commuting.
4.1. If you are a member of a small resistance unit that is fighting an interstellar alien invasion and a journalist (who's in bed with said aliens) approach you, it's perfectly OK to acknowledge that you are a member of or has direct contact to the resistance and to defend it's actions - such as the alleged killing of innocent bystanders - and if said defense requires you to reveal information that only the resistance would know that is OK too. After all, journalists have a strong sense of ethics, and if not they are usually too daft to take a hint.
4.2. It is also a good idea to meet with said journalist as close to the clubhouse (see #3) as possible.
4.3. It's OK to ask the journalist to pass on a fake message to your collaborators abord the alien space ship in order to create a diversion, even if it pin-points where said collaborators are located (in the medical bay).
5.1. A sniper located 100 meters from his target will be unable to see or hear any other people shouting or motioning directions to each other and/or the target.
5.2. If a sniper located 100 meters from his target somehow IS able to see or hear people shouting or motioning directions to each other and/or the target, the sniper will simply assume that all the shouting is unrelated to what he's currently doing - even if the shouting discloses (in every detail) a hair-brained plan for how to catch said sniper.
6. Aliens have never heard of CCTV and subsequently they have not realized how such equipment could help monitor their own crews (and visitors) as to prevent the resistance unit from spreading through the ranks.
7. If you are a bearded member of a small resistance unit that is fighting an interstellar alien invasion and a sketch of your ugly mug is shown on all TV-channels around the world there's no reason to stay out of the streets nor (just brain storming here) shave as to make yourself look different from the sketch.
8. If you are an armed member of a small resistance unit that is fighting an interstellar alien invasion and you find yourself in the same room as the Queen/Evil Leader of said aliens it is better to stare at the Queen with a frown than to pull your gun and blow the lizard's brains out and end the invasion (after all we got renewed for a second season so there will be more opportunities...)
Edited 3 total times.