I assume everyone who's competing already knows about Submittable....but maybe not. Signing up with Submittable is a good way to find suitable competitions and track your entries. You can create an account for free, and then select the categories you're interested in - e.g., Fiction Short Stories. You can also indicate whether you are looking for submissions without a fee, or whatever.
After that, you'll get a list of opportunities - for now and later. And of course, it tracks your submissions - what you entered/when/result...
Apologies if this is a duplicate post...I haven't yet figured out how to search previous entries.
If you sign up for their newsletter (also free), you get a regular email with a list.
And... I just noticed that they solicit posts for their blogs! and even pay if they publish. 600-1000 words is their preferred length. No reposts from other blogs - new material. Read the attached link for more, and be sure to check out previous posts to get a sense of their style. Submittable Blog Posts