Good things to do,

Use a template and study the template ingame and in flat form to get an idea where things will go in, It's much easier to also resize the template at width 1024 and height 512.

Here's already a pre-made one with those dimensions in spoiler below


Also looking up texturing tutorials on the forums

Decent tutorial here
http://forum.toribash.com/showthread.php?t=91748

But just play with it, you should get a hang of basic things and move up from there as you go.

Lastly just practice and have fun with it.