In general:
If at the current moment you can get information about candles and indicator from the history, do that, this is the best way
Using Variables to store states. You check some condition and set the value of some Variable to something, this is entirely custom. In other blocks you check what is the state (the value of the Variable) and depending on that you do something else. The downside is that if MT4 crashes, Variables are gone, they are temporary memory.
This
https://fxdreema.com/demo/mt4-wait-crossovers. But here all steps must happen one after another. I mean, block 1 will not run again until block 2 passes.