D&D 5E Any guides on making adventures?

[Reynard]

This is stated above but cannot be overstated: playtest.

If you can make up a story, you can write an adventure. It's really that simple.

But you need to playtest it thoroughly. Repeatedly. With different combinations of characters and character types.

And at the end of the day it's a judgement call - a well-coordinated group decimating your adventure with no trouble doesn't necessarily mean its a bad adventure. Luck happens, and you can't account for everything. Bit the only way you'll ever really see potential holes in your stuff is to playtest it repeatedly.

It is a little off topic, but the same should be said for classes and other mechanical toys. We are going to see a lot of ideas hurled up onto the DMGuild with little to no actual playtesting and they are going to end up creating problems for players down the line. Monsters are not so problematic because usually they exist in isolated encounters rather than across whole campaigns, but even they should be run against a few different groups of characters at different levels to make sure the CR is right or if a nifty ability is a TPK instigator.