If you're updating the setting of this site to the Exodus Era, then you will be pleased to know that there are no actual rule changes that have to be made. In fact, not a lot has to be altered. Instead if you're playing a Colonial character, the following might be useful.

After the destruction of the Colonies, what was left of the Colonial Fleet (i.e., the Galactica) needed all the help and manpower she could get. While she was short on equipment as well as men, there was a lot of work to do if she was going to rebuild. As a result of this, the military drafted in as much help as they could get. This meant that certain restrictions on entry were paid to rest. What this means for character generation, is that if you're creating a military character, you can forget about a lot of the restrictions for entry. You still have to be reasonably fit and be able to work, but the military are after your skills rather than your body. In addition, you will not get the training at the military academy (because there is no military academy) but you will be able to enter certain designations. These include the Colonial Army (not tanker), Shuttle pilot, Medtech and starship crew.

You will not be able to join the Colonial Warriors without being able to fulfil all the normal criteria though - flying a fighter pilot is not like dusting crops.

Once the initial hurdle of Carillon was past, the military would get their training regimes back up to full strength and nearly all entry restrictions would be back in force, although some of the physical ones might be a little more lax than normal. The Galactica has full training facilities on board and so all normal training (like the military academy standards) would be back and characters from this era should be built as normal.

Obviously though, some civilian designations will have no place in a ragtag fleet, and thus characters without a suitable designation will have to retrain in something to make them useful.