If the strategy is within your risk limit, then testing begins. Manually go through historical charts to find your entries, noting whether your stop loss or target would have been hit. Paper trade in this way for at least 50 to 100 trades, noting whether the strategy was profitable and if it meets your expectations. If it does, proceed to trading the strategy in a demo account in real time. If it's profitable over the course of two months or more in a simulated environment, proceed with day trading the strategy with real capital. If the strategy isn't profitable, start over.
The commission structure for options trades tends to be more complicated than its equivalent for stock trades. Until the commission cuts that swept the industry in the fall of 2019, most brokers charged a fee for each leg of an options spread, plus a commission per contract being traded. The per-leg fees, which made 2- and 4-legged spreads expensive, have been eliminated for the most part. We are seeing some brokers place caps on commissions charged for certain trading scenarios. 

Fortunately, at least in the United States, investors do not have too much to worry about when it comes to account security. This is especially true when choosing a brokerage that is large, well known, and properly regulated. Every website should be secured with SSL encryption, and client data should be stored in secure servers. Dual-factor authentication and Face ID are other security protocols quickly growing in popularity.

A broker is simply a licensed person through whom you can buy and sell these stocks. When you use an online platform, it essentially acts as an online broker. If someone wants to buy any product, he can contact a brokerage service. They would place an order and let him know the market price of the product. If the investor is interested, they would include a commission for themselves and process the order forward. If the user wishes to buy stock, the broker would forward his order to a stock exchange, which would approximately take 3 days to complete including the money exchange between the broker and the investor.