Since you land in Second Life with a skin, shape, eyes, clothes, etc., those really are a given. They may be ugly as all get out, but you have them.
Personally, I think every avatar should have an operator (the RL person at the keyboard) who has at least a vague idea of what they want to do, learn or get out of Second Life. There is a lot more information about Second Life on the Web than there was just a few years ago. Whether it is socializing, shopping, combat, sex, building or roleplaying, a person needs to have an idea in the back of their mind. All the material things will come with time and will change many times with each avatar as they evolve.
A Short Story of My Start:
I started in SL in 2008 with no clue in my head. I was curious about Second Life so I made an avatar to check it out... And I was completely lost. After going through the basic Tutorial that was offered, I knew I wanted to get rid of the "duck walk" ASAP and I wanted to know how to stop my hands/head from moving (typing) when I chatted but I had no idea of how to accomplish them. There really wasn't a lot of information available beyond the "How to move/chat/fly" tutorials. Or if there was, I never saw it.
Luckily I landed at a location that had a very nice, very helpful person there, a Mentor. This person spent a couple of hours answering my (and other peoples') noob questions. They gave me a Folder with a Basic AO, a few pieces of freebie clothes/hair that were a big step above the Library stuff, some landmarks to various locations as an example of what you could accomplish within Second Life (these were just really cool builds as examples of what users had built) and a couple of landmarks to some newbie friendly stores and clubs.
Without this person, I probably would have logged out and never logged back in. With them, I made a couple of life long friends and learned that anything was possible. Where only your own imagination, or lack of, is your limit.
I don't know how things are now when you first enter Second LIfe, but being greeted by someone who cares enough to point you in the right direction or offer suggestions, is invaluable.