As has been pointed out, the jump between each biome is fairly significant.

Valheim really is a game of preparation or foolhardiness, whichever is your preferred playing style. The first option is grindy but necessary if you want to have an easier time of things.

As a solo player, these would be my 3 top tips for all progression through each biome:

1. Max out all work benches per biome as soon as you can.
2. Max out your current gear and armour before moving onto a new biome. (Do yourself a favour and look up the vulnerabilities of the mobs you encounter so you can fight them effectively.)
3. Prepare the best possible food that you can make.

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4. For the Black Forest in particular, if you can manage it, sneak in and snatch any and all materials that you can find but remember that the more noise you make, the more mobs will find you, particularly at night time.

5. UTILISE THE RUINS IN THE FOREST. I cannot stress that enough. Make shelters along the way and mark them, that way you have somewhere to run to for cover or to sleep. Moving around the Black Forest at night is a bad move for lowbies.

6. When searching for copper, make sure you dig out the node completely - they're huge and go deeper than you think. This will save you a lot of searching because you can generally get most of the copper you need for making out your gear from one node.

7. Stick to the forest coasts when searching for tin, it's usually the safest part of the Black Forest. Tin is generally found in the shallow waterways you might find in forest valleys, too, however going inland can run you into more mobs that you possibly don't feel like dealing with.

8. Troll hunting in caves is the easiest way to get troll leather. You can cheese it by jumping in and out of the cave every 30 seconds or so. They won't follow you out.

Hope that helps.