Stupid Newbie Questions, The Prequel: Mass Effect 1

Asari Writing you can get just by scanning planets from orbit:

1. Porolan (Macedon System, Artemis Tau Cluster)
2. Ploba (Anteaus System, Hades Gamma Cluster)
3. Paravin (Hans System, Gemini Sigma Cluster)
4. Klencory (Newton System, Keplar Verge)
5. Matar (Hong System, Armstrong Nebula)
6. Junthor (Gagarin System, Armstrong Nebula)
7. Veles (Pax System, Horsehead Nebula)
8. Pataiton (Vostok System, Maroon Sea Cluster)

Some of the above clusters open up only after either Feros or Noveria main missions are completed (that is; there are terminals on these missions that open up some clusters on the Galaxy Map)

That leaves only two you need to get while actually landing on a planet:

Sharjila (Macedon System, Artemis Tau Cluster) - UNC - Asari Diplomacy mission (given to Shepard by Nassana Dantius after 1st main plot missiom completed; will influence some dialogue on Thane's recruitment mission in ME2)
Ontarom (Newton System, Kepler Verge) - UNC - Dead Scientists mission (is the background mission for a Sole Survivor Shepard; depending on decisions made, it may result in Shepard receiving an email in ME2 from Corporal Toombs)
Tuntau (Phoenix System, Argos Rho cluster) - Wrex - Family Armor mission (equivalent of a loyalty mission in ME1, may affect the status of Wrex later on in ME1, depending on Shepard's ability to charm or intimidate or lack thereof)

These planets also have asari writings, but the main missions on these planets are part of sequence involving missions first on still other planets that don't have Asari Writings:

Solcrum (Grissom System, Armstrong Nebula) - last planet in a 5-mission series that acquires Tali's data and results in an optional dialogue path in ME2)
Altahe (Acheron System, Styx Theta Cluster) - 2nd mission in a 2-mission series that opens up after Noveria plot mission is completed
Nonuel (Plutius System, Hades Gamma Cluster) - Renegade Morality Alignment mission, requires a certain level of renegade points to unlock (planet contain 2 sets of Asari writings)
Chohe (Cacus System, Hades Gamma Cluster) - Paragon Morality Alignment mission, requires a certain level of paragon points to unlock (planet contains 3 sets of Asari writings)