Anyway, to business.
When you read something out loud it's massively different to how its read in your head. You'll find those repetitions (if there are any) immediately and errors will scream out to you and of course to the group as well. Writing groups also help you build your confidence. One of the reasons I write is because I could never express myself through any other art form and when you read something you've penned yourself to a group, you're certainly letting some walls down and if your group is nice, they won't mind at all. In fact, they'd probably encourage you to be yourself. I'm a member of the Yeovil Creative Writers group and its the best thing I ever did for my writing. Well, that and reading 'Looking for Alaska'. Anyway, when you get feedback on your own work you'd be surprised just how informative it can be. I remember when I read out my first piece. It was from a dystopian novel which won't ever see the light of day and although I did get positive feedback, they also told me that I had fallen in a ton of traps. I tended to 'tell' instead of 'show'. I used cliches, 'scared to death' was one I remember and I also repeated words all the time. I also liked narration a lot and found my own back story fascinating which of course if told in large chunks, isn't actually that interesting for the reader. Now, I narrate less and my dialogue has improved, in fact, I prefer writing dialogue just like I prefer reading it. You'll find that nine times out of ten that using dialogue is 'showing' rather than 'telling'. I'm still trying to wrap my head around the two...
I've recently joined two book clubs where I live and both have been enormous fun. I think its important to find people who love books and writing just as much as you and when those stars align, the effects are beautiful. Better still if you have close friends who love books. Writing is a lonely undertaking and its important that one finds people who not only get why you want to write books but people who also want to write books. Not only are you making new friends but you are also networking. Networking, even though I hated the phrase at university is, well, I wouldn't say vital but certainly useful. The more people you know, the more fun your creations will become because you'll get that buzz and jump on your seat clapping your hands, 'someone can read what I've written!' Well, OK. Maybe that's just me.
Seriously, do search out writing groups. Of course you don't have to but you also don't have to drive but it does make life easier (speaking as a non-driver! What!). You might think you have the best story under the sun (and you may do) but you may not know it is filled with pointless back story and cliches. You may not know because you haven't realized how much there is to learn about the craft. I guess the main point is to find a learning platform that works best for you. I'm not the most social person in the world and I often find crowds quite intimidating and yes, the writing group did frighten me to begin with but when you regularly show up, put yourself out there and take the bullet (cliche?) you may feel differently. I did and my writing has grown and grown. Also its worth mentioning that when a group praises you on your work, no, scrap that. When someone praises you on your writing, it's a gigantic boost in confidence. You feel you have to relearn how to write again if you join a writing group but would you rather relearn how to write or continue to write below your potential?
That's up to you.