Okay, so you have a great main page, 40-50 pages, you have about 1-3 editors, now you are ready to get big.
You and your editors
Set up a chat on your wiki for you and your editors to talk. Figure out a specific time, day, month, week, etc. In that chat you should talk about pages to create and pages to expand.
You know all those pages you created before, that were just stubs. Well, know, you and your editors should expand on these articles, one line at a time. Infoboxes are a great way to get people interested. Make sure that your infobox is not too long or too short.
Okay, so you should have about know 75-100 pages. This is the fun part. Look through all your pages and decide if there are a group of articles that seem alike. Like, if you have a tv show, you should categorize all the characters, episodes, and producers. This makes it easy for people to navigate through you wiki.
Okay, you got pages, category's, and images. But not enough pages to request a spotlight yet. The first thing you should do is create blog posts on similar wikis (that probably have more editors and pages than you) and request that your wiki becomes afflites with the new wiki. But don't start out to big. If you have a gaming site, you probably shouldn't go strait for the Gaming Wiki. You want to start out with someone that probably has about 200 pages.
Soon or a later, you should hit 200 pages. Though, don't immediately go to request a spotlight. If you have an idea about a whole category and different pages, create those pages first, then request a spotlight. The people that put spotlights on are looking for a fun, learning encyclopedia about a topic, not a wiki that just simply's follows the criteria (even though it kinda is like that).
Don't make getting a spotlight your first priority when you create a wiki. Create goals for yourself. If you ever get bored of your wiki, start a discussion about one of the newest episodes (if you have a tv show wiki), or work on the forums. Your wiki is endless, do what you want with it.