Tiny Forge is based on Twenty Twelve, so many tips are valid. The only thing you will have to be aware: header.php element
<hgroup> in Twenty Twelve is called
<div class="site-branding" itemscope itemtype="http://schema.org/WPHeader"> in Tiny Forge.
Best practice is to create a child theme, copy header.php to it and make changes there. If you will edit directly Tiny Forge theme files, they will be overwritten with the next update.
Also think how this logo should be displayed on different devices, you may have to add additional styles under media queries in style.css