PONE makes textures because of Jesus

Looks okay for the start, to make it tileable isnt that hard when you learned the basics.

Tipps for the texture: The big black "holes" around that leaves should be a transparent so you see the bricks still ( 50% ) try it out

You chose an hard one to start!

To make a texture to tile, the only system i know is to offset the canvas in PS, so that you have your left and right seam touching in the middle of the image (in this case, if you need to tile vertically also offset vertically). Then you play with the clone-stamp tool and make it so there's no seam. To test it i'd make a pattern and apply on a new document.

Problem I encountered is that the result can be smudgy.

Back when HL mods where in full swing i used a bit PhotoSeam that does a few things automatically, dunno if it's still supported.

Not easy task working and achieving a great result with just a couple of photographic layers, I stopped texturing because my attempts where always too noisy by working only with photographic layers.

Anyways, I think it would be best for you to first create the brick wall, then apply the vegetation on top. This way you can have two elements to mix and match... and I guess it would make your work just easier.

My experience is very basic, i just did a couple of sets for good ol' HL, after that I still sometime do tiling to use in compositions, so I (yet) dunno the complexities and implications of normals, specular etc., but for the articles/tutorials i've read here and there for curiosity, I think this diffuse texture is too saturated and especially there are too many shadows that could appear odd in-game.

Yeah to make textures tile I use the same method as Blackdog mentioned above. Offset the image so you can see the seam then remove the seam using clone stamp and such. I also found the result to be blurry sometimes.

I suck at texturing though. Hopefully someone comes in and drops their awesome knowledge on the best way to make things tile nicely for you!

You don't HAVE to model or sculpt for your normals. Yes, that's probably going to give you a better result more often than not, but it's also good to know how to get a good normal map using heightmaps and NDO or Crazybump. What ever gives you the result you're looking for, sometimes some quick photoshop work will get you what you need.

Argh, I think my words were not understood in the right way.

I said that for a particular case like this texture ; A brick wall with foliage over ; I think the best way to achieve this is to separate the foliage from the brick wall (more easy to deal with and the final result is more modular) and to modelize some very simple leaf in 3ds max, bake them on a plane, and work with to create something more consistent to finally get a Foliage model to put over a Bsp wall (since you work in Source engine). For organic things, modelizing is certainly the best way to have something very clean with good relief. For the rest, ndo still very great.

Even combining these two very different material types into one texture might be a strange jump off point. In practise you'd probably want to separate these two into different objects,tiling brick wall texture for BSP with a foliage mesh over top it or at least a blend shader with two different materials. Combining varied texture types into one material can sometimes be a bitch with physics materials for sound/hit effect reactions etc.

Maybe pick a simpler starting point. Like, just make the tiling brick wall texture or something.

Way to jump into the deep end man wearing no speedos.