I normally play only 1 character at a time. If there are 2 characters they can help each other, but a single character do not benefit from this help.

There are a few things that can amend this situation. But remember, this is not official rules.

1. Give the character an extra action. This I think is a bit too much, as there are cards that can give a character one extra action.

2. Give the character an extra trait from one of the other Characters. This is also a bit much in my opinion, but it is possible.

3. Give a character an extra +1 on one skill, max skill must not exceed 4 in this adjustment.

4. Why do enemies deal damage without a skill test?. Such a skill test should work in the same way as a normal skill test, but using the enemy´s combat skill against the characters skill + a token. Characters can not get any help from cards. Tokens with a plus becomes a minus and only numbers (mostly minuses) from the Scenarios Reference cards are used. A few examples. The Ghoul Priest (Combat 4) against Jenny (Combat 3)

   Skill test 4 + token -2 = 4 +2 = 6. So Jenny get damage.

   Skill test 4 + token +2 = 4 -2 = 2 The Priest fails.

   Skill test 4 + token +1 = 4 -1 = 3. Success for the Priest.

Token Autofail is also an automatic failure for the priest.

An Elder Sign would also be a failure against Jenny if she had 2 or more resources.

I am not sure if this works in all scenarios, but the characters have a chance to defend themselves.

5. There are probably other ways as well. I have not considered any more, but it is up to you.

6. A combination of 3 and 4 is what I have been playing lately. It helps somewhat but scenarios can be difficult enough, even if only at Standard mode.

First, those are interesting Ideas, Second "Standard" is misleading because standard difficulty is still very challenging especially solo. The enemies hitting you automatically is a theme choice to me, you are a normal person, not a super charged hero, fighting creatures/gods that are supposed to have powers beyond our comprehension, the fact they automatically succeed when they hit you is just one of the strengths they have against us. Just MO but it helps immerse me in the world a little more when I'm sure it was just a balancing mechanic.

Yes, a solo character cannot benefit from another's help. That's why you build decks differently according to the number of characters. A solo character is also only drawing 1 card from the encounter deck each turn (which means fewer enemies in play) and needs fewer clues to advance (and deal less damage to "boss" enemies to defeat them).

with respect, you maybe ought to learn the game a bit more before jumping to conclusions and adjustments. I've read a few of your recent topics and they leave me with the impression that you are pretty inexperienced. You also need to remember that no game can be made with perfect equality for both sides (even in chess, somebody gets the first move), but that doesn't mean it isn't balanced. It's just part of the game, and it's not unfair just because it's different.

As mentioned, solo players come with their share of challenges, but they also have their share of advantages when compared to multi-investigator teams. Lone Wolf, Scrying, A Test of Will, and Ward of Protection are all significantly more powerful in solo play.

I've seen a small handful of threads recently about ways to make the game easier. I always say that people can play the game as they like it (so long as everyone agrees!), and I stand by that... but frankly I do find it a little disappointing that people would rather invent new rules rather than learn how to play the game better. The game comes with an easy mode. Use it if you want to. If that's still too hard, then I feel there are probably aspects of your play that could be improved upon...

As others have said, "Standard" difficultly when playing solo can be very challenging. There is definitely no shame in playing on Easy or adjusting the Chaos Bag slightly, which has a similar effect to your point 3.

Solo decks do require careful consideration since they need some way of handling anything that the game can throw at you. This is made more difficult if your card pool is very limited. If you are finding that deck consistency is the problem (e.g. you only have 1 core set and not much in the way of expansions) then perhaps you could consider adding something like "[free triggered ability] Place 1 card from your hand on the bottom of your deck. Then, draw 1 card. (Limit once per round)" to your investigator.

I'm fine with enemies automatically dealing damage/horror. In most cases you have all of your investigation phase to figure out how to deal with them before they have a chance to do anything, and usually only one enemy will be showing up at a time.

Just play on easy dude. Arkham LCG is one of those games where "Standard" really means hard and "Hard" means Nightmare.