After playing for about 2 years (not steam recorded), I found the best solution for Roland how to survive. First things first, you will have to choose the correct skill tree points. Being level 68, this is how should it look like (left side, you can also click on it to make it bigger). Starting from level 0, I would recommend going after infantry till you receive 3rd tier, then go to medic skills and level up the same way as it shows in the picture. After upgrading infantry and medic you should go after support. And finally after you have upgraded all skills go after the last skill called "Refire".

• Infantry skills help you to reduce recoil, increase bullet damage and increase fire rate. Having these perks you will become more aggressive than usually since you don't want to break a killing chain and lose your passives. These perks are not stackable or activable, most of infantry skills are passive.
  
• Medic skills is going to heal you and your teammates as you rush with allies into enemy fortress. Every time you kill an enemy, you will gain healing passive with infantry passive. That makes you unstoppable killing machines in the hordes. Also this perk gives you health, ammo bonus and your converts your damage into healing damamge to your teammates so you can keep your allies on foot.
  
• Support skills also haves passive which will regenerate your armor for every kill, this way you will keep your health above 50%. With the help of stronger armor your passive becomes even more stronger. And with the last skill, it will increase grenade damage and regenerate grenades which can be used to heal yourself or/and teammates.

Since you are Soldier, your main weapons are going to be: Assault rifle, SMG rifle, Shotgun and your favorite weapon. Sure, you can change your weapons by your taste and how fast you act in game. Shield is always going to regenerated after a kill, so you don't have to look at regeneration status, take highest capacity. A mod for a soldier haves to be "Support gunner", with this mod you and your crew will never run out of ammo and keep the pressure on the enemy. Weapon requirement should be:

• Damage - High
  
• Accuracy - 70+%
  
• Fire rate - ~5+
  
• Ammo - 25+

Shield:

• Capacity - Highest
  
• Recharge rate - 150+
  
• It can be elemental

Class mod:

• 15+ Team Ammo Regeneration
  
• 3 skill point bonus if possible

Grenade mod:

• You can use any grenade mod. Note: Grenade damage can heal your allies.

This is my equipment that I use in a battle. As you can see, there is no Assault rifle. Assault rifle is best at low level/early game before you start finding legendaries. I use legendary hellfire SMG since it takes down enemy's shield quickly and starts burning their flesh. With fire weapons, fire stacks and makes a huge damage to your enemy and burns him to the ashes. So instead of Assault rifle I use rocket launcher to save myself with blast radius that can save you from bleeding out. I use explosive shotgun to make even bigger damage and radius so it's perfect against spiderants, psycho hordes and badasses. I use sniper rifle not because it's my favorite, but it's against gattling guns since they are strongest enemies I fight against, so with fire element it helps you to take cover and reload while fire damages gattling gun. I also use the strongest shield and a class mod that is a Support gunner.Lastly I use Tranfusion grenades in order to survive when I am at low health or enemy seems to be stronger than I am.
TLDR; My Bazooka is normal one, without elemental, SMG haves Fire elemental, shotgun haves Explosive elemetal and sniper rifle haves Fire elemental.

With these skills you can be as much aggressive as you like but watch out, you still have your limits
Tips for gameplay:

• If you are low on health, back off and throw some grenades.
  
• Turret is useless and is a weak distraction. Use turret when you are in tough situation.
  
• Don't throw turret when you know you are going into bleedout. You will waste your special.
  
• Stay next to your allies to keep on healing them.
  
• Watch for your allies health meter, you can heal them by shooting them or throwing grenade.
  
• Choose your weapon wisely, SMG against badass can be sometimes weaker than a shotgun from 30 meters.
  
• Cover can save you or kill you. If you are in the cover and below 10%, get out of your cover. Behind your cover, you can't shoot or see your enemies so your surviving chance will become less than 3%.
  
• If you are in bleedout, kill your main target as quickly as you can if he is below 20% health and he is not a boss. If not, don't kill main target, kill less weaker enemy around him.
  
• Jumping will help you to fight against assassins.
  
• Some enemies that are hard to hit have a second weak point besides head.
  
• Gattling guns, shock enemies and enemies with shield that absorbs any elemental are the strongest opponents

Pros:
You always fully supplied, you're team savior, keeping crowd control, can solo most of the bosses, you support yourself, keep all the loot yourself.

Cons:
You are most likely to lose in duel, your special is useless, melee doesn't do a lot of damage, skills only noticable after 1st kill.

A elemental weapon have burst fire like a rocket launcher. If your target is not visible (like in a video), you can still do damage without having a sight on him by shooting into ground near his legs or wall next to him.





Blast radius can save your life. If you have a strong rocket launcher, you can shoot into the wall, ground or ceiling to make blast radius, hoping that enemies who have low health are going to die.
(Example in the left)

• Green - You.
  
• Red - Enemy.
  
• Grey - Radius.
  
• Cyan - Aim.

Killing spree will always increase your accuracy, fire rate, health and armor. If you keep on killing enemies, they will do no damage at all.