The story quests should be pointing you in a couple of different directions by now. You should be equipped enough to follow either of those at this point.

The overland route specifically will net you plenty of shrines along the way to continue pumping up your hearts - there are a few caves too and those are always full of surprises.

Just be smart about what fights you take on along the way. Two things about fights in this game:

1. It's okay to run. If you encounter anything you aren't prepared to fight, just run. Typically you can get away on foot (or horse if you have one). If it comes down to it, warping away is also fine.
2. Especially in the early game, fights are trial and error. And you aren't going to find the loot you're looking for without taking on fights. You're probably going to die a few times, and that's okay.

The game doesn't punish you for dying, unless you're overly sensitive to loading screens. Try different strategies, get a feel for the advanced combat mechanics. You'll probably end up at a few different combat training shrines if you're following the early game quests and that'll help you out if you're unfamiliar with some of the more advanced techniques.

Are you fusing things, like monster parts, to your weapons? This will make a huge difference.

Other than that, just play the game. Do shrines to get more hearts and stamina. Explore, then you'll automatically find better armour, or you'll be able to buy it.

Some mini-bosses, like lynels or Gleeoks, will simply be too hard for you know. Others, like Hinoxes, should be doable if you know their weak spot.

If you go to the woodlands stable, just a little north of Hyrule Castle, you'll find a Great Fairy who can upgrade your armour. That should help you survive a little longer.

Additionally, there are several ponds, both in the sky and the surface, where you can find regular fairies. Sneak up to them slowly to collect them, and then you have a safety net against instant death.

In the depths, try and gather as many puffshrooms as you can. These explode into a cloud of spores on impact, and enemies within will lose sight of you. Then run behind everyone and sneakstrike them, and that will take out most standard enemies. If need be, it also makes it easier to flee.

Just explore and do shrines, sometimes raid enemy camps, and fuse stuff to your weapons.

Or really just take it at your own pace and don't sweat it; sounds like you're in early game.

Where can I get decent early-mid game loot?

There is a large, secret explorable zone accessible via Lookout Landing that has a full set of high defense armor hidden throughout it. I found that set very useful for early and mid game.

Make sure you're always fusing, especially decayed weapons + monster parts, drastically increases durability and damage.

And cook!

Something I didn't realize till recently, but there is a game mechanic that doesn't let you get one shotted at full hearts. Keep cheap food and top off every hit. I found that easier to do and build stamina until I could get better weapon fuses, armor, and enough hearts to not get 2 shotted.

Also always try to keep a fairy on you.

Muddle bud is a life saver.

Most enemies in camps go to sleep at night (Bokoblins and Moblins, but not Lizals) which gives you the opportunity to sneak into the camp, take their weapons and just leave. No fighting required. You can also steal stuff from a Hinoxes' necklace if you manage to land on his chest without waking him up.

If you're adamant about killing them still, crouch down and sneak up to a still sleeping enemy until a button prompt appears onscreen that reads "sneakstrike". Sneakstrikes deal eight times as much damage as normal hits but still only consume one point of durability, which can make it easy to take out an entire camp without even fighting.

Did you find some elemental items already? Shock fruit, Chuchu Jelly, the like? Use them. You can fuse them to arrows or just toss them at enemies manually, and each has some neat extra effects that deal extra damage, stun your foes, or can even OHKO monsters of the opposing element (fire/frost). Be careful with shock-type items tho because it's easy to get yourself zapped.

I've found horses to be a good way to take out Boss Boko groups. A sprinting horse tramples your enemies which deals damage and can knock them down / make them drop their equipment, and melee weapons deal double damage if the horse is at least cantering. It's also harder for them to hit you while you're on horseback.

Use the environment to your advantage. Rolling or dropping heavy boulders on foes, shoving / luring Bokoblins and Moblins into water to drown them (they can't swim) or tossing them off cliffs might be easier than just fighting them head-on, especially if you're dealing with a group.

... but like others have said already, there is absolutely no shame in avoiding fights altogether until you're better prepared, have better equipment and stronger armor and more skill. There is plenty of other stuff to do, a whole lot of shrines, puzzles, sidequests, minigames and general exploration that doesn't require you to fight anything, but will still make you stronger in the long run.

Honestly making your way to the castle in the sky and heading to the throne room. You can sneak around most enemies up there and get high end gear

Grab a weapon base from the depths and fuse with enemy loot with whatever good attack power you have available. One handed weapon and a lot of shield use is safe. Keep yourself at max health after getting hit. Defense up with foods or elixirs.

Find a direction where you can manage the enemies. NPCs try to give you a lot of hints