How to make a 256x256 texture to better 512x512

[Emperor Domitianus]

As the tittle says i was wondering how to make a texture from it's default 256x256 to a better 512x512 one with out redoing the whole texture.
If there is a guide or you know how to do please explain me.
I am looking mostly foward making the soldiers textures to a higher quality where needed.

[Halie Satanus]

You just make a copy of a texture and resize it to 512x512, then you re-texture over the original.

These are examples of what can be done, though obviously they're UV mapped.

Spoiler Alert, click show to read: 

[Emperor Domitianus]

I though it was possible just to make a better 512x512 texture by just adjusting the pixel resolution of a texuture without reteturing the model again....
So this means that if I have a 256x256 can't improve it with just adjusting the resolution?
If yes, how?

[tone]

No, just making it 512x512 won't help unless you improve the textures. All you'll do is magnify the graininess

[A.P]

wait, how do you re-texture over the other one?

[Emperor Domitianus]

Yes true. How to do that? What I would to do is to increase the quality of the textures by making them better with the resolution. For example like the Ferres ones...

[Halie Satanus]

You can't make a low resolution texture better, it is what it is. You can add your own on top which is why using 512x512 is preferable. In the example I posted on the right I made those leather straps myself from scratch, I couldn't have got that much detail in a 256x256 texture and reducing to that size would have lost quality.

If your just asking how to make such textures, I use layers create a shape ie; an oval and then use burn & dodge to give it a 'look'.. sometimes I use bevel and emboss to give it depth and drop shadow to make it sit on top of whatever it's on top of.. (you need a tutorial really.)

[Mithril]

yep layers is the only way to go to make the textures better got it from one of the greatest unit maker here but he is gone for so long