I have been earning a living from my writing since 1998. You would think that by now I would know everything there is to writing, but the simple truth is that a writer never stops learning. Here are the things that I do to increase my writing skills on an almost daily basis.
Read Books on Writing
It sounds too easy, but it is true: reading books about writing will help increase your writing skills. I have a library of books on writing. I also look for free Kindle books on writing on a daily basis. I can plow through a Kindle book about writing within an hour, typically. I also make weekly stops at the used book stores and buy up any writing and style guides I don't already own.
Take Online Courses
A quick search through Udemy.com will bring up a number of paid and free grammar and writing classes. I have taken a bunch of classes through Udemy, including 2 classes on writing. I highly recommend that you check them out and try out a free course or two before you commit to paying for a course.
Keep on Writing
Write as much as possible. Practice really does make one close to perfect. Try and find someone who will edit your work. You will more than likely have to pay for this, but just having someone correct your writing and studying where you made your errors will help you target your weak areas. You can use Fiverr.com for editing and proofreading services.
Read Your Writing Out Loud
A trick that many writers use is to read their material out loud. This not only helps you pick out errors, it will also help you find trouble spots that need correction.
Another trick that I use is to have my computer read my writing back to me. On my Mac, I write my blog posts in TextEdit. When I'm finished, I select Edit at the top of the screen and scroll down to Speech -- Start Speaking. I can pick out lots of errors just by listening to my blog being read back to me.
Don't Give Up
The worst thing you can do to yourself is give up. I am telling you right now that it possible to improve your writing skills. All you need to do is continue to learn, continue to write, and stay determined. Admitting that you need help with your writing is a great first step. Now, get to work and begin improving your skills and yourself.