Feepness -
          Definitely water, desert, land, and mountain. When playing a
          "Jovian" race, you really can't go wrong since there is a
          very high percentage of gas giants out there.

  Lestat -
          Always choose the ones which are best for your planet type;
          those are cheapest. I don't recommend buying more than one
          other sector compat, if even that, since the *number* of
          compatibilities you have is a factor in point cost as well.

  Keskiolut -
          Main preference plus one or two another ( take 100%, because
          they're cheap after the first 30% or so... ). So, maybe a
          desert and forest. Or another good choice: desert, land and
          mountain.

  Neue Regel -
          For a Class M planet, take land, water, and ice. These are
          very common to the other planets too. Forest can also be a
          good choice.

  Garfel -
          with desert: land/mountain; with forest: land/mountain/water;
          with earth: land/water/mount (mount is not important but has
          high resource content).

  Cylons -
          Recommendations for these are plated, land, and water. You
          should have compatibility with these three sectors before you
          choose others. You don't need 90-100% on every sector type
          you do choose. You can select 50% or lower so you can make
          use of the few odd sectors, or asteroids, forest planets,
          etc. . . Ice is a good one, since it shows up on iceballs and
          most class M planets on the poles.

  Thing -
          Pick as many sector prefs as you can; get them to at least
          25%. The best ones in my opinion are home planet sector,
          desert, mountain, land, forest, water then ice.

  Muu -
          If you don't have a sector preference in a certain sector
          type, you effectively can't live on those sector types. So,
          if you can afford it, buy some compatibility in all, or most
          of the sectors. They don't have to be bought at 100%. 10%-20%
          should do for most of them. Be sure to get one or two
          sector-types at a high compatibility, such as 90%-100%. If
          you live on a Class M, I would suggest land, water, forest,
          and a little desert. Again, if you can, get at least a little
          in all the sector types.

  Fnebish Legion -
          I mentioned this a little bit before. Land and forest have
          the highest fertility (I'm not mentioning gas since, if you
          take a Jovian race, gas is your only viable option), hence
          can support more population. This is good for races with
          collective IQ. Mountain and desert have high resource content
          but low fertility, so they're good for races with high metab.
          Ice is useful since it is found on almost all the planets in
          at least some small amounts, and water is a good choice for a
          race starting on a class M, though it is generally poor in
          resource content. Select an unusual mix and you'll find
          working with allies much easier.

  Microbians -
          Similarly it's not a good idea to be compatible with every
          kind of sector. MANY alliances are based on sector
          incompatibilities.

  Tribbles -
          See comment to question 3.

  NB -
          Land, forest, and water are my favorites.

  TheCulture -
          100% for your "home" sector type (i.e. water for water worlds
          etc.), and at least 50% on a couple of others. "Land" and
          "Mountain" are pretty good choices, since they are quite
          common. Again, this depends on your play style. You can
          either invest a lot in sec. preferences and be able to
          utilize pretty much anything right at once, or you can invest
          in tech and build Terraformers as soon as possible (with
          Terraformers you can change sector types into your own
          preferred sector type.

  Froos -
          Try to include either land or mountain because many of the
          asteroid/ iceball type planetary bodies will have one of
          these two sectors on them.

  Griffons -
          Totally dependent on your home planet. The more the better
          but you will find that some sector preferences cost too much
          due to you being on a planet that does not have the sector
          much. You will get the idea if you try having a desert home
          and water compatibility. Water tends to be one of the most
          common (generally supports high pop but low res production).
          Forest is the same as water but supports a higher pop and is
          very rare (throughout the universe, that is). Land, is
          incredibly common with average pop and res production. Ice is
          common, supports little population but high than average res.
          Gas is only good if you are a Jovian race: low pop/sector and
          low res. Mountain his high res and low pop. Desert same as
          mountain but generally more res.

  Pillarian -
          Depending on what race gen is being employed will depend on
          you avenues of decision. These mainly being that you will
          require 100% of the main sector(s) of what ever planet type
          you have chosen. Ie class M land(*) or mountain (^) on the GB
          enroll system. Variances have and will occur in the 2 main
          race gens available.. (GB's { code, and Clay's port driven
          system).

  Tao -
          I've had quite a good start with starting on earth and being
          able to use water, desert and land. Deserts could be changed
          to mount, maybe. That way you can land on most planets, get
          resourceful sectors (desert) and still can spread well on
          your home planet (water).

  Empire -
          As many as possible so you have wider basement when you start
          to colonize other planets..... Mountain is
          resource-rich and quite a non- rare sector type, but it costs
          points. If you take gas, you don't need to take any other
          sector types.. :)

  Link Baker -
          Water is pretty abundant in the universe. Forest is rare.
          Choose water, and then land or mountains. Stay away from rare
          sector types.

  Greenies -
          Besides your planet type sector, definitely choose mountain.
          There are mountains on every planet, and asteroid.

  Zurgithian -
          The primary sector type must be 100% i.e. on Water planets
          have water 100%, forest 100% on Forest planets etc. On Desert
          planets you can usually have desert, mountain or ice as 100%.
          For metas it is good to have some compat with forest as your
          population grows fast because of the high fertility. Always
          go for some on land ! If playing HAP have some mountain as
          there is lots around.