Assign roles to your fighters and build them for that purpose, picture how each ship is going to act in each turn, and look for unusual synergy.
Look for EPT's which bounce off pilot abilities, look for pilot abilities which complement each other, look for EPT's and pilot abilities which boost the power of generics.
Two hints when building your first lists from scratch:
>Create an 'alpha strike' pilot
You want to create a pilot who can throw the most red dice possible at your enemy as close to turn 1 as possible. There are many ways to do this, discovering them is part of the fun of building lists.
>Create a 'control' pilot
Once you have your 'alpha strike' create a support pilot who has the ability to 'control' enemy movement. You assert this control by forcing your enemy to become stressed or ionized, which limits their next maneuvers.
Attached is an example of an 'alpha strike' and 'control' elements in a list:
Wedge throws out 3 red dice, which is good but not great. If, however, you can get him in the right position, he reduces enemy green dice by 2, which makes his 3 dice more valuable.
When Wedge makes his alpha strike, Jan Ors uses her pilot ability to boost his attack by 1. So Wedge now throws out 4 red dice - even better with the enemy down 2 green. Note the synergy between her pilot ability causing stress, and stress triggering the EPT Wired.
Gray Squaddie has an Ion Cannon, Flechette Torpedoes, and R3-A2 - in the right range bands, this will deal 1 ion token and 1 stress to your target, or 2 stress to your target, which severely limits their movement for the next two turns.
Always aim to have your lists on 99 points. You want initiative if your best pilot has a higher PS than his, you want to give him initiative if his best pilot has a PS equal to yours.
Be warned: building the 'perfect' list will consume your life.