EDEN PRIME - No choice of companion.
CITADEL - Initially no choice of companion, but this will change.
Don't fast travel; using the elevator will unlock further missions.
For a future interaction, follow the Garrus lead first.
There are hackable consoles around that unlock more missions.
After dealing with Fist, pick up something in his office.
Be sure to go to Flux.
Speak to as many people as you can find.
There's lots of missions to start in the first citadel visit.
You should return to the Normandy with three more companions.
When you get back to the Normandy talk to everyone (this will be a recurring theme, so get into the habit of this).
FIND LIARA T'SONI - take anyone you would like.
When you get back to the Normandy talk to everyone.
BRING DOWN THE SKY
Go to Exodus Cluster, Asgard System.
Be patient with the combat, this is early to do this mission but it helps to improve your rep.
UNC MAJOR KYLE
UNC HOSTAGE - Kaiden has unique dialogue.
UNC MISSING SURVEY TEAM
UNC ROGUE VI - I like to take Garrus because of a future mission. Remember this mission because it is referenced by a character in approximately 100 hours.
When you get back to the Normandy talk to everyone. You should pick up personal missions from Garrus and Wrex.
RETURN TO THE CITADEL - Take whoever you want; I think having Garrus here is funny, but they all do fun stuff. Garrus and Wrex are a great combo here for the whole time back on the citadel.
There are a lot more things that you can do, so wander around a lot.
You may have unlocked further dialogue options with points in charm or intimidate.
When you leave the Citadel for the Normandy, you should have picked up UNC Privateers, UNC Asari Diplomacy, and UNC Hostile Takeover.
UNC PRIVATEERS - Take anyone, but a mixed squad is good.
Go to Horse Head Nebula Cluster, Strenuus system.
This mission can be tricky to find - you want to scan an area to the left of planet Xawin and then you will be able to continue the mission.
UNC ASARI DIPLOMACY
UNC HOSTILE TAKEOVER
Base 1 is in Gemini Sigma Cluster, Han System.
Base 2 is in Hades Gamma Cluster, Dis System.
Final Meeting - Horse Head Nebula Cluster, Fortuna System.
RETURN TO THE CITADEL
UNC LOST MODULE - Thematically Liara works here but she doesn't have exclusive dialogue.
FEROS
Go to Attican Beta Cluster.
All four assignments are done before using the elevator.
Search the room with the varren in it.
If you're using Garrus, make sure by now he's able to wear Medium armour because SERIOUSLY.
Gavin Hossle has a mission with an impact on a future game.
When you get back to the Normandy talk to everyone. If you didn't get the mission from Wrex you should have it by now. The Council will also want a word.
UNC EXOGENI FACILITY
UNC COLONY OF THE DEAD
UNC LOST FRIEGHTER
UNC ESPIONAGE PROBE
Go to Voyager Cluster, Amazon System.
There is a jumpscare in this mission, even being warned about it isn't enough, I jump every time.
WREX: FAMILY ARMOR - Wrex and anyone.
GARRUS: FIND DR SALEON - Garrus and anyone.
UNC GETH INCURSIONS - I take the same people for all of these even though they're mostly Mako until the end. As it's Geth, tech works best.
When you get back to the Normandy talk to everyone.
UNC DISTRESS SIGNAL
UNC DERELICT FIGHTER
BACK TO THE CITADEL
NOVERIA - Initially Garrus and Wrex switching out one of them for Liara later on.
There are a lot of different things that you can do in the Noveria base.
Once you are able to leave the base to get further towards your target head back to the Normandy and change either Garrus or Wrex for Liara. You want her on this mission.
When you get back to the Normandy talk to everyone.
UNC LISTENIN POST ALPHA
UNC LISTENING POST THETA
UNC MISSING MARINES
BACK TO THE CITADEL
UNC CERBERUS
Go to Voyager Cluster, Yangtze System. (You may need to jump to another system to get this to open up.)
Really pay attention to these Cerberus folks, I have a feeling they might pop up again.
UNC HADES DOGS
UNC DEAD SCIENTISTS
Depending on your Paragon/Renegade level, you should unlock either:
UNC BESIEGED BASE (If you reached 80% Paragon, or 90% after reaching 80% Renegade - only possible with mods.)
Hades Gamma Cluster, Casus System.
It's difficult to complete the secondary objective - I shut my companions behind a door.
UNC THE NEGOTIATION (If you reached 80% Renegade, or 90% after reaching 80% Paragon - only possible with mods.)
Both of these missions have an impact on future games.
DOUBLE CHECK YOUR JOURNAL TO SEE IF THERE IS ANYTHING LEFT TO DO AND DO IT
VIRMIRE ***THIS IS THE POINT OF NO RETURN*** Take whoever you want, this is an important mission, they each have the same amount of dialogue.
You will not be able to leave the citadel to do further missions after Virmire so make sure you have done everything that I have listed above.
Make tough choices. The things that happen at Virmire have a knock on effect through the entirety of the rest of the games. Good luck.
When you get back to the Normandy talk to everyone.
BACK TO THE CITADEL - Take Ashley and Wrex if you would like to.
If you have anything to turn in make sure you do it now.
There will likely be some more conversations that you can have in the citadel.
Make sure you have spoken to your biggest fan three times.
Buy the Elkoss Combine license from Expat in the Market. This has an impact on a future game.
THE FINAL MISSION - Liara has a substantial amount of exposition dialogue but honestly this is the final mission take your pals.
CONGRATS YOU COMPLETED MASS EFFECT - ON TO MASS EFFECT 2!