Here are some tips and tricks to help you survive the Night Market and earn favor without needing to be an endgame player.
Earning Favor
You won't be able to earn as much favor as someone with a dedicated group, but there's still plenty to earn in the districts. There are a number of daily quests that you can pick up in each district. Many of these don't require combat although some will be difficult to get without it. There are others though, like cooking a meal and dropping it off that will give you a nice little amount of favor without requiring you to fight.
There are also a number of bosses scattered through the district that will drop rewards. There are areas near each of them with little to no enemies. You can wait in stealth for a crowd to arrive or join a group finder group to tackle these bosses without needing to talk with anyone else.
Finding a group without needing friends or a guild
There is a new section of the activity finder called "Event Zone," and there are constantly groups running. If you want to ensure that you are in a populated instance, you can join one of these groups and help out. Many of these groups are NOT dedicated groups doing specific activities but other solo casual players like you just loosely grouping up because there is safety in numbers. You can even leave them once you're inside and as long as they aren't delisted, they'll be able to continue to find members. And you'll know there are other people in the instance. So, don't feel obligated to remain in the group for hours. You can join them for a boss or two and then leave. Just be polite and don't join a group that has 11/12 members if you plan to immediately ditch ahead of time.
If you are in a guild but don't feel like going with a guild group because you want to play by yourself, you can also use "Travel to Player," from the guild roster. This will put you in the same instance as your guildmate. This way you're less likely to end up in an empty instance but can still do your own thing.
Gear and Skills
There are some gear and skills that are fairly easy to get that can help you die less often. None of this requires instanced group content to obtain. Although you may need to take on some older world bosses.
Overland Sets
Ring of the Pale Order This mythic ring will heal you as you deal damage. Having passive healing can be a huge aide in staying alive when you're fighting. Just take this ring off if you decide to join an activity finder group that has a good healer in it.
Oakensoul Ring This mythic ring gives you a number of damage and survivability buffs that will help you defeat enemies. The most notable of this is empowered, which will supercharge your heavy attacks allowing you to save your resources for defensive skills. However, it limits you to one bar.
Briarhear Set This set also gives you passive healing for doing critical damage. Not the best set in the game but if you're struggling to stay alive in Nightmarket, it is a solid option for staying alive. It pairs well with the Order's Wrath Set.
Vesture of Darloc Brae - This sets reduces the radius that you can be detected by enemies and restores stamina and magicka back to you while crouched. You can pair this with invisibility to sneak past enemies.
Nightmother's Embrace - This set reduces the radius the radius that you can be detected by enemies and reduces the movement penalty of sprint. This set is excellent when paired with Darloc Brae to allow you swiftly and easily avoid enemies. However, you'll hit like a noodle so only fight bosses in large groups.
Crafted Sets
Tideborn Windstalker This set gives you a pretty substantial and passive buff to your direct damage skills against npc enemies.
Order's Wrath This set gives your crit, raising your damage against npcs substantially (and it's better than similar overland sets). It pairs very nicely with the briarheart set.
Highland's Sentinel Another strong crit set. Stronger when you aren't moving but even without stacks it's decent and easy to get.
Skill lines to consider adding to your arsenal
Sorcerer - Storm Calling - Critical Surge - This skill allows you to passively heal as you do damage while active.
Nightblade - Shadow- Shadowy Disguise - Most of the trash packs in the Night Market can be snuck by using invisibility. Shadowy Disguise allows you to maintain that invisibility for as long as you have magicka.
Dragonknight - Draconic Power - Disintegrating Dragonfire - This is a widespread continuous beam channel skill. In addition to looking like you're a cool flamethrower, this skill is excellent for allowing you to take on the trash packs because you can keep on the move while channeling it and it doesn't require empowering ahead of time.
Dragonknight - Draconic Power - Take Flight - This ultimate ability will knock the smaller trash enemies up into the air, so you can use CC to even the odds. Additionally, it dramatically increases your damage done against them. When paired with the skill line passives, it will also restore some hp and resources back to you. This is a very powerful line to subclass into.
Arcanist - Herald of the Tome - Pragmatic Fatecarver - The infamous beam that hits a bunch of enemies at once and grants you a damage shield at the same time. Needs to be empowered by a crux builder first. This remains a solid option but for Night Market, since you're playing by yourself, I actually recommend the DK beam more as it doesn't require the delay in powering up. Nevertheless, this remains a very solid and popular choice for solo casual play as it is hard hitting, grants you survival, and hits multiple enemies at once.
Damage Shields - There are a number of damage skills in the game. Use them to get away from danger or help you survive particular big attacks. Use them as a way to enhance blocking and roll dodging rather than as a replacement for it. Which you'll want to use will depend on your build e.g. a stamina character may want to equip a 2H and use brawler.
Champion Points
Reaving Blows This slottable will grant you healing as you do direct damage. Found in the blue tree. Pairs nicely with the beam skills as they are considered direct damage.
Potions
Invisibility Pots and Tripots (restore stam, mag, and hp) are both of great benefit. You can also use armor pots for tough fights.
StrategiesSneak around when by yourself
Use stealth to get around trash packs in the Night Market. If you don't care about doing high damage, you can make it even easier to sneak around using the sets listed above. Wait for larger groups to engage in bosses and then join into the fight or join a group in the group finder to take on bosses. You'll find players running around either way. If you'd prefer to hold your own when fighting the district bosses, I recommend equipping the more damage-oriented sets instead. While you're waiting for groups, do the daily quests to continue to earn favor without needing to fight so much.
When fighting, don't move around excessively
You don't want to pull multiple trash packs by running around too much. Pay attention to your surroundings to avoid aoes and running into more trashpacks. You can circle strafe around the enemy in a tight circle to avoid damage by movement while still not pulling other things when necessary. Block and roll dodge are good for getting out of high damage scenarios like aoes. If you're having trouble seeing the AOES, you can customize their colors to something you can see better in your settings.
Use Activity Finder to locate populated instances
You may not want to be in a group with people, but you also don't want to be by yourself all the time. Join an activity finder group or create on yourself. You'll find a bunch of people doing their own thing, but just in the same area.
Use the jump pad to get out of danger
If you've accidentally bit off more than you can chew. You can run to a jump pad and whatever was chasing you will stop once on top. Use a damage shield to survive the brief stun when using one.
Look for buffs
There are races and puzzles that you can take on that will offer you powerful buffs. There is also the werewolf behemoth buff just lying around. Take advantage of these to enhance your strength.
Get Passive Healing
This guide offers a number of suggestions for getting yourself some passive healing that heals you up while doing damage. But it is far from an exhaustive list. You know your character best so find ways to add passive healing to it if it is not high already. There are a number of sets and skills in this game that offer it. Passive Healing will be one of your best friends in the Night Market because it will allow you to thin out enemies while preserving your resource so that you can use your damage shields and other defensive options when you need them most rather than spamming them.
Conclusion
You don't need trials, arenas, or dungeon sets to do just fine in the Night Market. But you may want to adjust your playstyle to add sneaking and passive healing to make trash packs significantly easier to manage.