I'll go against the grain here and recommend you play chaotic evil rather than good,
since that will give you more options for both ranking areas and also behavior
in game (you can kill anyone you want).

Since you want to learn to solo rank there's no point in grouping with others.
Both ranger and assassin can solo rank fairly easy to mid 30s, dextrous
ranger all the way to low 40s. After that it gets time consuming (still possible) so if you're easily bored it pays to have a group.

You *don't* need to rank to hero though, and in fact, I don't recommend you do, since you're a new player. There is lots of fun to be had with both classes below level 40.

One thing that is different in CF than in most other muds, is that some classes gain nothing from ranking to hero and in fact lose a lot of their power by heroing (due to
a combination of other classes reaching the pinnacle of their power at hero, getting no good skills, other players having more health, gold, preps and being more skilled in general and so on).

Ranger is one of these classes. Unless you want to lead a cabal or are badass enough to have killed enough people to distend (meaning you enter the PK range of players a lot higher level than you), you should not hero a ranger period. Rangers are at the pinnacle of their power around 35 (when they get wilderness familiarity) and for *some* combinations at mid 40s. Beyond that they're progressively weakened.

Also, some ranger combinations (this also applies to other classes e.g. thieves and shapeshifters)
are completely useless for certain things (such as playerkilling) so keep that in mind. I would suggest
forester/survivalist felar to start with. Stay away from mariners, bedouins, plainsrunners and caverndwellers.

So if you play another ranger, make it your goal to solo rank to 35 and get wilderness familiarity. Then you can play around more with the class and have some fun, solo or with others.

If you play another assassin, rank to 35 and experiment with stalk/assassinate.
Then 40 and play with owaza.
Then 44 and do the same with martial trance.
Then you could try to hero an assassin since it's not as bad as ranger at hero.

For assassin i'd recommend felar or human.