Starting a Corp. Brokerage Acct Tips

I hope all are having a nice Tuesday.

I have an LLC for IC work that I do, so I was talking with my CPA about how best to do some basic trading. He said to open a Corp. Brokerage Acct, so I'm wondering if anyone on here could give me some tips on how to get started and things to avoid.

I have a personal Fidelity Acct, that I dabble in some more long term investments, but I'm looking to do more day/swing trading. Basically I'm looking for more of a hobby. I have friends that do Fanduels, etc to make games more interesting, but I'm not that much into sports. I do have a very amateur enjoyment of economics and the market, so I guess this is an option. Not looking to make a living out of it, but something to keep my mind churning daily I guess. Not looking to put to much into it, but maybe $3-5k to open the acct, and do small trades to start to enjoy it.

Anyway, I was wondering the process for creating this kind of acct, and what all is needed from my end other than my TAX ID#. Is Fidelity (Active TraderPro?) the right way to go or are there other options that would be better? Would be cool if there was a good APP to move pretty fast with.

Lastly, any operational/process dos and don'ts from any of you that have a trading businesses that you would tell your younger selves?

Thanks!