I am curious to hear about different approaches for identifying key price levels in the markets that you trade.
I identify them by price action generally. More specifically, I look for long price action entries in uptrends and short ones in downtrends, choosing my entry right after small retracements in bigger trends. (That's only
one way of doing it, naturally, and not the
only way, but it's a pretty reliable one.)
What are other methods and tools that you use to determine key levels?
I don't really use "tools" other than in the sense that all charting is a kind of "tool" by definition.
How do you determine which ones are significant and which ones are not?
By backtesting and then forward testing the very few methods that convincingly pass the backtest without significant drawdowns along the way.
In other words, "objectively".
Even though both backtesting and forward testing are less than 100% reliable.
One does one's best to approximate "reliability" and "robustness".
The methods that appear to have a sound underlying basis (e.g. of the kind described above) and that show profits without serious drawdowns, first on backtests and then subsequently on forward tests, are the ones that
almost certainly have a genuine edge.
Nothing else is likely to have a genuine edge at all.
Personally I don't let it get any more complicated than that, and I look for near-certainty rather than for certainty.
Once you've got as close as you realistically can to proving that it has an edge,
and working out appropriate risk-management and trade management parameters for it (this requires some mathematical/statistical understanding which needs to be learned first), then "doing it" is trivially easy and even boring. It's "
learning how to do it" that's difficult, time-consuming and demanding of acquired skills that none of us was born with.
The mistake many people make, in my opinion, is starting to trade whatever-it-is
without doing all those other things first, just on "hope" or - even worse - on "ill-informed belief" (and often without
really having learned the skills to do them). And the realities of the market predicate that that's never going to work well in the long run, even if one gets lucky briefly.