Understanding Stats?Follow

It varies depending on what you want to do with them, with yourself, and your personal habits both naturally and combat wise.
Say you want to be primarily an artisan with some combat skills.
Keep Mind and Action up high, then try to max out your 2 skills under each. That will make it so you use less points for action and less for mind. While also regening them back quicker.
If your primarily combat as it sounds, then go for the best HAM (Health, action, mind) while keeping all the other stats as high as possible. For example My Wookie on Bria has 800 in HAM, yes has 500 in all the others. Thar way he uses less points and regens them faster while hunting or doing Artisan or Bio Engineer skills. While maintaining a decient HAM so I don't get incapped within 1 hit. Except for Stormtroopers. They like doing that.
So it varies according to your style, habits and tastes.
I'd suggest focusing slightly more on your HAM sub-stats and put the rest in HAM. Just My personal play style.

As far as stats go doing hard missions the best bet is as high as you can in the two lesser stats. Con/str for Health etc. That way you use less and regen faster. I have around 800 HAM on HAM and around 500 on the lesser.

Two other things have made a difference for Me in doing difficult missions. One, a weapon that does good damage with really good speed. I find that shooting 20 times doing 200 damage is better then shooting 10 times doing 500. because you might miss while running so the extra 10 times makes a difference. And if you are using a pistol then first shot should be a bleed shot. Get there health going down. Then run away as often times 4-5 will come at you. Keep running away and around so that you are never too far from your mission waypoint. Now if you can use covering shot then do so. That lowers there stance. Works great on the brawler types of mobs. Try to get them all bleeding if you can. Then use a full power shot now and then. The main thing at that point is run and run some more. Standing still is a death wish. If you can spare the training I'd suggest taking some medic so you can use stimpacks to heal yourself during combat. Just set the stim in a hotbutton and click it, then click empty air so it won't think you're trying to heal the enemy.
The two biggest things are: fast/high damage weapon and bleed shot. If you can't bleed shot yet then run and shoot alot.
If you start getting too beat up, run away and keep running until they either stop chasing you or you incap. Then once your safely away kneel or sit down until your health is ok. If he's bleed he'll be down alot of health. And you'll have regained yours.
The hard mobs solo take alot of strategy as opposed to might. I enjoy soloing but learned alot reciently while fighting Force Troopers. 10k HAM and they team up to hit for 500, sometimes as much as 1500. Insta incap. However if your more then 70 meters away you may not get deathblowed when you go down. If they start walking towards you and keep on comming then your doomed.
Hope this helps some. I can only tell you what I've learned in My travels. Need any more help just feel free.
I play on Bria server by the way. Sometimes Scylia. Let Me know if you play on those and if you're looking for some help covering the tush.

Might I recommend a bit of spice, until something more repspectful comes your way. Its like armor in a can. I like to keep a neutron pixie on my belt in case things get ugly so can I...

Look I have a way
If you become a weaponsmith you can make your own weapons and customize them making your pistols and specials go to your customitivity preferences