I will describe here steps I made to make my galleries for my first WP theme. I wanted to have a few links in my menu which will take user to page with thumbnails. Each thumbnail takes user to gallery with bunch of horizontally displayed images.
First, in my functions.php file I've added new size for my icons:
add_image_size( 'wide-image-icon', 200, 150, true );
Then, I've made my template file for gallery category (lets call it Gallery1) and category "Gallery1". In my gallery1.php
template file I used query for posts with galleries:
query_posts(array('category_name'=>'Gallery1','posts_per_page'=>-1))
Then, in posts loop I've displayed my gallery icons (which are featured images of posts):
the_post_thumbnail('wide-image-icon');
So now, after creating new page with "Gallery1" template, I can add post, select "Gallery1" category for it, add pictures using standard "Insert gallery", choose one as featured image and I'm good to go.
The problem is that's not universal way of doing this. What if I would like to make another gallery page (Gallery2). Then I need to make new template file, create new category, change category name in query inside template file, add new page with this template attached to it. How do you do it?
I'd also like to ask about some admin side improvements for gallery. I've seen themes where there was a completely new tab inside admin area where you saw all galleries, you could easily change images order, add/remove galleries etc. Right now on my website I add my news ( I use the same system here ), galleries, blog posts and normal pages like "Bio" as posts only which is definitely not good.
PS. Any articles, video tutorials, books or tips and tricks are welcome.
@edit: How can I manage display of my galleries on admin side? I'd like to remove whole editor and leave just pictures if you know what I mean.