What I'm going to say isn't a recipe for success or popularity, but this is what I do, and this is what feels right to me.
I'm a firm believer in writer's and reader's integrity. That is to say, I won't write a flattering review on a sub-par work just because its author is popular. Similarly, I won't flatter someone just because they wrote a positive review on my work. I will, of course, be nice and friendly and appreciative, but I won't say something I don't believe.
On the other hand, I will go out of my way to read what really interests/impresses me. I'll even go as far as reading in Spanish, Italian or French, languages I'm not exactly fluent in, if a translation isn't available.
I hope people read what I write and comment on my work because they enjoy and appreciate it, not because they expect me to read and review their work in return. It comes down to this: I'd like to gain readers who find my writings enjoyable, fun, worth reading without any ulterior motive. Just like any good book. And such readers are truly precious to me.
About writers' contests: I generally don't participate in them. Or rather, I only participate in those where I can give a sample (chapter, paragraph, favorite quotes) of what I've already written. I do not have the time or energy to dedicate to "write a fun story about an important figure in your life" challenges.
Not to say such contests are necessarily a bad thing. On the contrary, they can be fun. But currently I'm operating on a very, very tight schedule. On any given day, the number of diapers I've changed will usually be higher than the number of pages I've written. So I have to concentrate on some serious writing and reading of the good stuff I really, really want to read. Otherwise, I'll find that another day has passed without any productivity on my part.