Before even worrying about Cap skills, you should be training all relevant support skills to 5. Anything dealing with your tank, weapons, capacitor, fitting, etc. should be at 4 or 5 depending on the skill. Just dont gimp yourself by neglecting some basic, shoulda trained it years ago, skill.
This way, you will actually benefit from your training as you go. Training carrier 4 before say, drone skills, doesnt help you in the mean time. By training all the functional skills first, you can benefit from them while the skills that are capital specific are training for weeks on end.
The basic skills that are a must for all caps are:
-Jump skills: bring them all up to 4, but 5 is better. Coordinate with your FC's to determine what will be expected during ops
-Boosters/Drugs/Implants: long story short, they save ships. The slight boost in abilities they provide often is the difference between a successful cap, and a flaming wreck.
The amount of time needed to fly a cap successfully varies with the ship. I wouldnt recommend flying any of them until you have brought the specific ship skill, jump skills, and most of the weapon/tank/module skills up to at least 4. These ships are massive liabilities, and losing one because you didnt put the 3 days into a skill is plain stupid.
Dreads will be the least skill intensive overall. They dont require many skills by comparison, but those few they require should be brought up to 4/5 asap. These include the skills needed for siege and their weapons.
Carriers are the next step up in terms of skills. To fly one well you will need good drone skills as well as all the remote repair skills (depending on the bonuses of each ship), consider triage as well. Some pilots swear by it, others swear at it. It is largely situational.
As for super caps, plan on spending a long, long time training for them. Given the amount of money put into them, flying them with anything less than maxed skills is looked down upon. You would want just about every skill at 5 or close to it (super carrier 5/titan 5 and other very long skills can probably be trained while you are flying the ship, but that is up to the pilot)
As others stated, EVEmon will be a big help in planning all of the skills out, just make sure the projected training time doesnt get you down. In the end it isnt that long, but man is it worth it.