In my opinion your greatest challenge or concern is understanding the market itself, not brokerage firms, not trading platforms, market data providers, etc... very often newbies bog themselves down with so much information that has nothing to do with making money, i recall when i was studying for the real estate exam and then finally became an agent, the day to day activities connected with being a real estate agent had nothing in common with what i was studying for,
it had no practical value.
roll up your sleeves and burn the midnight oil, make copies of market data and study it like a book, scrutinize it, get to know the markets intimately, smell, touch, eat, breathe the markets.