There's still good traffic and sales in gallery submissions. But you have to do it almost every day. One or two galleries a week won't help much.
Since you're a beginner, I would recommend using
Chameleon Submitter. That will create the preview thumbnails and replicate your gallery with all the recips in place. It'll submit the gallery to 100's of sites. You don't have to worry about conflicting rules. You'll enter the gallery information, and it'll only submit to the correct sites. It looks a little confusing at first, but just follow the tutorials on their website.
Eventually, when you get some experience, you'll want to start getting partner accounts. Some sites offer free PAs and others will charge a monthly fee. But I wouldn't bother with this until you know what you're doing.
And if you're going to submit galleries, make sure your hosting plan will handle the traffic load. Galleries will quickly eat up a ton of traffic. You might get stuck with huge overage charges. Or if you're on a shared/virtual plan, your host might suspend your account due to overloading the server.