You buy a call if you think SPY goes up, a put if you think it goes down. That part's simple. The real skill is deciding direction, and doing it from structure and the tape, not a hunch. Here's how to think about it.

The mechanical part

Call = a bet SPY rises (the call gains value as SPY goes up). Put = a bet SPY falls (the put gains value as SPY drops). For a scalp, you're picking the direction of the next move you expect, then buying the matching option. That's the easy half — the hard half is being right about the direction often enough to matter.

Deciding direction from structure

Good direction calls come from reading the market, not guessing. Use the dealer structure: Is price above or below VWAP (buyers or sellers in control)? Is it bouncing off a put wall (favor calls) or rejecting a call wall (favor puts)? What's the gamma regime? Is a level being reclaimed or failing? Direction should follow from where price is in the structure and what the tape is doing there, not from a feeling or a hope.

Call or put is the easy question. “Which way, and why?” is the whole job — and the answer should come from structure, not sentiment.

The quick takeaway

Calls for up, puts for down — but decide direction from the structure and tape, not a guess. That's the real skill, and it's exactly the read NoVo is built to support: it maps the dealer levels and reads the tape so you can make an informed directional call, then scores its own read afterwards. The tool gives you the map; the direction is your call.