I have read articles on the pros and cons of making my freelance a business/LLC. I am the only one so wondering any tips or advice from other people. Should it be an LLC or S corporation or just money under the table(jk on latter)?
A lot of people put a lot of money and effort into creating the appearance of a business without ever making an actual business. You can develop some basic groundwork without an LLC, business cards, an office, staff, debt, liability, etc. When you need business-y stuff like deposit slips, staff, office space - look at it then. Probably not while you are alone in your garage with no revenue.
You should protect yourself with a corporate entity. The reason is that not everyone is nice or understanding. One issue with a contract and you could be sued for more than they paid you. As far as what type of structure, LLC is the easiest to create but you should ask an attorney in your area which is best for you.
Totally depends on your risk exposure. If you're building websites for massage therapists and not making a ton... probably not a requirement. If you are building applications for businesses that do a lot of revenue and are mission critical - totally make it official.