Selfelected

Download the templates from Tangible, there is a gratis version.
Use the Simple and the Advanced templates from Tangible.
Read Oleg’s article.

You might notice that T4 once in a while complains about a right parenthesis. This is often a false error. In some cases you get more errors so just skip to the right-parenthesis-complaint and they will vanish. Other cases this is the only error. Just type a character and delete it and save again. It can even be enough to just step away from the edited row.
The error is always on the same row as the cursor is positioned.

If you know that the output should compile but the compiler complains every time you save the .tt file it is working as it should. Saving the .tt file runs the template transformation but doesn’t start any compilation. So just compile after saving the .tt file and all should be well.