As previously stated the Basic Skill plan of Part allows you to create a character that can sit in a Super carrier for around 4b ISK but sitting in the Supercarrier is a far cry from being able to actually being a useful holder character.
Basics are just that
The basic skills needed for sitting in the hull are just that, basic, if you want to make your character more attractive for someone to purchase you need to inject additional skills and train a few of the basic ones to higher levels.
A side effect of the missing skills is any modules dependant on them will be offline when the holder is in the ship but when swapping in a character that does have those skills they will remain offline and have to be onlined manually. Without the aid of a mobile depot/Ship Maintenance Array this is problematic so having skills for all fitted modules on the holder toon is highly recommended.
What To Train
|Thinking, Pondering, Working out what to do|
Armor - everything except Armor Laying and Amor Resistance Phasing (to IV) to V with Capital skills to I
Drones - Fighter Bombers I
Electronic Systems - Electronic Warfare to V and Projected ECM to I
Engineering - Everything except Advanced/Weapon Upgrades, Nanite skills and Thermodynamics to V with Capital skills to I
Navigation - Evasive Manoeuvring V, High Speed Manoeuvring to III and all Jump Drive skills to V
Shields - Shield Management V, Tactical Shield Manipulation V
Spaceship Command - Capital Ships V
We don't need to have perfect skills, Level I is basic is enough (it will be the responsibility of the buyer to further train, if they want) for most skills but there are some pre-requites skills that we do need to get to IV or V to unlock the next skill book (Fighters is a good example, we need it to V to unlock Fighter Bombers).
All up this is another ~190 days training that will need PLEX and skill books for but will make your character more appealing to those interested in a "pre-packaged super character". It is totally optional to do but if you're looking for maximum investment return (and remember this is a long-term investment) then doing this will be something you'll want to do.