Are you upgrading your skills?

This.

Just don't break the game, ok? I'm sure it'll get better.

Borderlands 2 has severe balancing issues and is much easyer in multiplayer mode.

For me it was quite easy the first playthrough and also well playable the second playthrough. But it became painfully hard to reach levels over 50 and it took me a very long time to reach level 72.

Doing the raid bosses in ultimate vault hunter mode is almost impossible in singleplayer mode. Even worse, there is almost no chance to solo the digipeak structure challenge to get those overpower levels because you have to complete it without a single death or you will be restored outside the challenge. Multiplayers can revive each other. 

If you do the same challenge in multiplayer mode, it may happen that you just run into a party finishing the chalenge so without any effort you may gain a overpower level.

Some tips for first 2 playthroughs: 1. If a weapon does not work, get a different one. Look for legendary weapons. Almost every boss drops them from time to time. You should google for the legendary weapons and where to get them.  You have to do the same boss over and over again. This is part of the compeltely fu<ked up game mechanics. For example, the easy boss Knuckledraggers grops the hornet, a caustic multy fire weapon. You just have to beat him several times and pray to get one. So the game mechanics contain something called drop rates. Maybe there is a 5% chance to get a Hornet when beating knuckledraggers. So you have to beat him again and again until this gambling finally gives you the gun you wanted. This problem is called drop rates and i will never ever buy another game containing droprates. It is like gambling. You invest your time and then the dice (randum number generator) are rolled and you see if you have had luck or not. If not, you invest your time again.

Even worse: those weapons loose their power quick. In Borderlands 1, which i can recnomend very much, it was possible to pick a decent weapon and keep it a long time. Somehow the devellopers did not like the idea of players using a weapon for a long time and thus the weapons loose their power fast when you level up. Due to the issue called "Droprates" you do not see many decent weapons from normal gameplay.

So i reconmend the following strategy is an enemy is to strong. 

1. Use other weapons. Use Weapons which fit your level. Look for special weapons outside the questlines by repetedly killing bosses. Please use google for legendary loot positions. Very nice is "infinity pistol" from dr. mercy or hornet. 
2. Use a different element.  google for the vulnerability of an enemy. Fire weapons do not work well on fire enemys for example.
3. Inform yourself about the weak spots of the enemy
4. Level up somewhere else. Then return. In the first 2 playthroughs the enemys do not level with you. 

Never be afraid to get stuck. When you die, you will get new ammo. And you can die forever, even if you completely run out of money, you can die and get revived again. 

Never think you are a noob, this game is so insanely wrong balanced, depending on the situation (what enemy and what weapons you have) it can be way to easy or much to difficult. 

Also it is possible that you have skilled your character in a wrong way. Then change the skilling.

As i said above, the game should be playable quite well up to level 50, after this point it is going to be painfully difficult and only slow progressing. Getting to level 72 is a pain in the A$$. 

If you like multiplayer gaming, the game is easyer, much easyer. But if you hate multiplayer gaming like i do, then it is extremely difficult and not very responsive. That means, if you get struck, the game does not help you. 

Dont wast your time to google for glitches, they have removed them all. 

Borderlands 1 was a very good game. Borderlands 2 could be so too, if they would not have messed up the balancing completely. I am not going to buy future gamed from gearbox. They are making multiplayer games. The singleplayer campaign is only there to force them players into multiplayer mode i guess. Everything is much more easy in multiplayer mode. 

There is someone at gearbox who decides this game to be a pain in the a$$, screwing up the balancing by rendering weapons worthless after only a few levels of progress, introducing insane droprates to force people to spend their time doing the same boss many, many times to get a orange weapon just to throw it away some levels later because it is even wors than white weapons of the actual level. They also patch away every little glitch that may help the players to beat the game.

Dont waste your money and time with gearbox games like a possible borderlands 3 and if you do, wait until it is very cheap. Kepp in mind, that you still will be challenged by problems with extremely bad balancing!

Golden Keys are not very useful, they do not give legendary (orange) weapons. But if someone is stuck, it is a good idea to invest them hoping to get a pülasma caster weapon, they are powerful but you need luck and many keays to get one. :(

Very much this. I don't mean to blame, but when one person complains about a lot of games being too hard and barely anyone finds the games too difficult, there's a pretty good chance that one person just isn't a very skilled player.

I've played through all of Borderlands 2 with all character classes alone. If you loot plenty and keep your weapons updated and also skill properly then it's not even close to being hard. Since I'm doing all of the side quests I'm usually overleveld for all main missions.

Pro tip, always max out your inventory and seek out the nearest shop. Then take your funds and play slots at Moxxi's. Great way to have some up to date weapons in green and blue and to farm eridium.

Just level up more I guess. Not really a difficult game.

Playthrough three is the definition of unfun difficulty. Something they really need to work on on future. And yeah some of the Boses can be problematic depending in the character you choose, thr best thing to do is just coop it. Makes everything better

I really need to get the Handsome collection. I played BL1 but got fed up of the driving sections as driving and shooting was too hard for me and I was going it solo. Up until then I was flying through the game doing all side quests, bagging bosses.

Have things changed for the sequel and prequel?

Only part I can think of that's hard is that Mad Mel boss.  Get a vehicle with a rocket launcher, use the "lock on target" button, and spam rockets.