that's cool for newbbies in that categorie !
But for models , in fact we tile the texture and do what we want , by
editing the UVs !!

And wings 3D is my best UVmapper tool : i apply 90% of time unfold mapping
for characters etc ...and you can edit UVs and export the UV texture
for painting above.
for levels some planar are enought; i highly recommend Wings3D (free tool)
and there are video tutorials about uvmapping