Check out the list op perks you want for you character and note their prerequisites. You can delay picking perks until you qualify for better ones. Some suggestions for a marksman:
FO1:
Bonus Ranged Damage (x2) AG6, LK6, Lvl6
More Criticals (x3) LK6, Lvl6
Sharpshooter (x2)PE7, IN6, Lvl6
Better Criticals PE6, AG4, LK6, Lvl9
Bonus Rate of Fire PE6, IN6, AG7, Lvl9
Action Boy/Girl (x2) AG5, Lvl12
Sniper PE8, AG8, Small Guns 80%, Lvl18
Optional:
Awereness PE5, Lvl3
Friendly Foe PE4, Lvl6
Tag! Lvl12
FO2:
Bonus Ranged Damage (x2) AG6, LK6, Lvl6
More Criticals (x3) LK6, Lvl6
Better Criticals PE6, AG4, LK6, Lvl9
Sharpshooter PE7, IN6, Lvl9
Lifegiver (x2) EN4, Lvl12
Action Boy/Girl (x2) AG5, Lvl12
Bonus Rate of Fire PE6, IN6, AG7, Lvl15
Sniper PE8, AG8, Small Guns 80%, Lvl24
Optional:
Awereness PE5, Lvl3
Living Anatomy Doctor 60%, Lvl12
Gain <statistic> <statistic> <10, Lvl12
Tag! Lvl12
FO Tactics:
Bonus Ranged Damage (x2) AG6, LK6, Lvl6
Sharpshooter: PE7, IN6, Lvl9
Action Boy/Girl (x2) AG5, Lvl12
Bonus Rate of Fire: AG7, Lvl15
Sniper PE8, AG8, Small Guns 80%, Lvl24
for recruits:
Mutate Lvl9
Tag! Lvl12
optional:
Awareness PE5, Lvl3
More Critials (x3) LK6, Lvl6
Better Criticals PE6, LK6, AG4, Lvl9
Lifegiver (x2) EN4, Lvl12
Divine Favor CH8, Lvl14
Gain <statistic> <statistic> <10, Lvl12