The first question I have to ask is what exactly do you want to write? Sometimes people want to freelance when in the back of their mind they're actual desire is to write novels. It's important to ask yourself some serious questions. I never did that and wound up writing in journalism, scriptwriting, broadcast journalism, technical writing, non-fiction--and my true desire was to do novels.
If it's novel writing, just start and work on finishing the project, then revise it. That's really the only way you will learn how to do it. You probably can't do this full time and will have to do it on the side. Novels have a huge learning curve.
If it's freelancing and you want to work full time, make sure you understand the implication of that. Sometimes people think they want to do freelancing so they don't have to work. You'd have to treat it like a job and literally work eight hours a day (or more) getting manuscripts done and out, researching, etc.
Critique group would help you best if you wanted to write novels. That's where you'll find most of them. Most of the freelancers are freelancing, not giving critiques; wheras with novels, you have a lot of novelists wanting to improve their skills and get published, so they're doing critiques (that's how you get better in your own writing, by the way--give critiques).
Better for online critiques is either Absolute Write or Forward Motion. Both boards are heavily moderated, so the critiques won't get out of hand. The best thing you can do if you want to get critiques is to monitor the critique section for a few months so you can see how things work. Then start giving critiques and participate elsewhere--you got to earn your keep.
