If you are in a spammy niche, then you can use almost whatever domain you want. Ideally, stick with at least wider niche relevancy.
In non spammy niches, you want your domain to be as closely relevant as possible. What tends to happen is that after a redirect, you receive an initial boost. Then however, gradually, your site will start losing rank.
Why this happens is, I presume, that the backlink boost is fast to catch on. However, with redirects you might dillute your topical relevancy, which takes a bit longer to catch up. Thus the gradual drop after.
And the way to do it is simple. Get a domain, rebuild it, use Archivarix for example. Let it just rest for a few months. Then write an article on your money site about the domain you want to redirect. Let it age a few weeks, then do the redirect. And that's that.