Getting to #1 for "sales letters" (pix enclosed)

When did you put the redirect in so that it goes from the .com to the /blog/? Looks like its still cached as of April 15 as the .com:

Sales Letters | Info on Sales Letters, Sale Letter Templates and Copywriting

Google might've already cached the page and its just not showing in the cache tool, but could be the reason why you saw a drop. To be honest, I wouldn't do the redirect unless you REALLY have a necessity for it.

As for links and such, you definitely need more, of course. With Google, it's always going to be about "signals of quality" (signals being links). You need more of those. You are going up against players that do have intense domain authority, but of course, it's do-able, you just need to go and get some authority links.

My suggestion: See if you can contact local newspapers and write something up about "sales letters" and see if you can get it published on there website or at minimum, a columnist's blog post.

Another suggestion is contact colleges and see if they'd like to use your website as a resource for sales letter information. Provide value and you'll get the links; simple as that really. Most people don't want to provide the value cuz it's too much work, which it is typically, but worth it if you want the rankings. I've developed all sorts of widgets that took MONTHS of development just to use it as a link building tool. Result: plenty of .edu and .gov links and top 5 rankings.