The site is in decline, yes, but so is the hobby in general.

Part of it is the Official Discord with its innumerable issues and the general movement of RPing toward Discord rather than forums.  Part of it is the season.  Part of it is an aging base.  Part of it is just the hobby itself aging.  This is still, for my money, the best site for the hobby.

With that in mind here's my cheap plug for a guide I wrote.  Well, a guide I compiled with advice from a ton of users here, including BrokenPromise, Kuro, Ammokkx and ERode

Cheap Plug - particularly the "Can't Find a Partner" section
https://www.roleplayerguild.com/topics/184596-rping-aint-always-easy-a-collaborative-guide-to-the-stuff-that-makes-t/ooc

In short though my advice would be to join one or two of the group RPs.  You may not be a huge fan of group RPs but just because you are in a group RP doesn't mean you have to split your interactions equally between every participant.  It would be wise to try to a little bit at least to sort of flex or stretch your writing muscles, but it's pretty normal for people and characters to form little cliques.

Writing with a group, and writing in general, gives you a chance to interact with others and see whose writing style you like and whose writing style you don't like, as well as further develop your own writing style and display it for others.  Essentially building a reputation as a writer with certain strengths and certain weaknesses.

There are enough writers here with enough talent that with a little work you can likely find your niche.