Images in google

hello guys
I'm a continous reader of this amazing site, I was reading for a long time, but now I would like ask a few things if it's possible.
first of all. sorry my bad english, this is not good but I'm gonna try to explain my doubts.
I have a wallpaper site, but I would like increase the rank and indexed pages on google, how can I do that?
I'm using wp as frontend and a self backend to connect and publish into the site, also I sent the correct sitemap with all posts, I've created another sitemap with images (following the google schema) and they both were sent to google by using the google tools for webmasters and by url as well. Robots was placed in the site and configured to allow be "crawled".
Everything is ok (I think), following some steps found in this site (keywords, friendly url, plugins, etc). Unfortunately I got 40 indexed images only and I have more than 400 posts and every post has its own thumbs (8 or 9), then I might have more images.
Also, posts are not being indexed as desired, I got one indexed page after 2 days I have another site and it's indexed after 30 mins or less.

Any idea why?, also any advice, question will be very apreciated.

Thank you in advance.

when did you send in the sitemaps?

Google take a long time to index pictures, i have pictures that havent been indexed for months, it seems to be easier if the picture already on the internet, but if you upload them your self it goes way slower

Try scrapebox + pingfarm.com

ronegraT: sitemaps were sent 1.5 months ago, every file has a friendly name.

IamNRE: I will try your advice, once I get some bucks, thank you.