What I do is I mark all the seams and hit Unwrap.
Here is an example UV Map I created:
Ambient Occlusion Map
I will sell these 3D assets I created to the Unity Assets Store. They are finished, I’m just UV Mapping them now.
Am I doing good?
It looks like there might be stretching issues, when unwrapping it’s best to make a new image and in the dialogue that pops up pick “color grid”, and apply that as the texture while you unwrap- that way you can tell if there are any places that are warped or stretched, or places where the pixels are too small or too large compared to the rest of the model. Once you’ve got that sorted out, you’ll want to re-arrange your map to make better use of the space, for example that yellow element that’s sticking out the top of the UV map could be shifted down to run along the side of the other islands, and then the whole map could be scaled up to fit the space better (thereby giving you more pixels of texture to work with in the same size image). In general the less empty space the better, although if you have to stretch or scale stuff too much to pack the space the extra pixels may not be worth it.
i agree that you should try to take more control over the process, by placing some seams of your own.
It’s a good idea to use the “numbered checkerboard” patterns as temporary textures on your models so that you can readily see on the map how the regions of the map line-up with the textures.
Now, for example, lay a seam down the length of the shaft and put the seams of each part of the shaft in the same position. Unwrap these in a cylindrical fashion. Separately unwrap the circular disc at the top, the face of the disc, and the cone (which converges to a point). And so on.
Then, y’know, actually try to re-decorate the thing. Starting with the checkerboard, is it easy to lay-in a texture such that parts do not meet “at odd angles?” When you find something that does not work easily, make it easier. But also consider which parts of the object are going to be “seriously on-camera,” such that a slight glitch would actually draw the eye. (This is, after all, a weapon that some bad-ass dude is gonna be laying into people’s heads most of the time …)