Good question. I was in the same situation before, until I decided to invest real money and power up some sp. But even now, I still focus on growing my own account by creating quality posts on a daily basis. But that doesn't mean I am not helping. I support many authors (most of them friends) by putting them on steemauto autovote. I run weekly games and give away SBD, just for the fun of it.

For a minnow, I know it is really difficult to grow (gain steem power). And your little sp stakes are, to be honest, worth too little to have any impact (upvote value) to anyone that you support. But providing support is not just about giving a $ value. By upvoting a good post, you acknowledge that it is a quality post. It is also important to leave a comment. To engage with the author and soon, your effort will pay off. 

I don't suggest joining a curation trail. Firstly, your upvote has little $ value. Second, there is no engagement done. The author doesn't know who you are, although you upvoted him or her. Instead, I suggest to do manual curation, AND, leave a comment for every upvoted post.

Another suggestion is to build up your reputation. So yeah, focus on your own development first. And help others by joining communities that help people.