The five columns that matter on day one: strike (the contract's anchor price), bid (what buyers are paying right now), ask (what sellers are demanding), mid (the midpoint between bid and ask, your honest entry estimate), and delta (the contract's directional sensitivity). Volume and open interest matter for liquidity — wide bid-ask spreads on illiquid contracts will eat your edge before you ever experience the strategy's math.
Practical rule: if the bid-ask spread is wider than 5% of the option's mid price, the contract is too illiquid for active trading. Stick to weeklies and monthlies on the major indexes (SPY, QQQ, IWM) and the most-traded large-caps until you have a feel for what tight markets look like. Liquidity is invisible until it isn't, and slippage on a wide chain can cost more than the strategy's edge.