The first leg should be obvious. You should not have to squint. Price and volume up together, preferably away from a level a lot of people are already watching: the premarket high, yesterday's close, or today's open.
The pause is what separates a flag from a spike you arrived late to. In the pause, volume should drop. The range should be clearly smaller than the leg. The lows should not collapse. A pause that lasts too long loses interest — then it is no longer a continuation, it is a new market.
The trigger is easy to say and hard to wait for: a buy when price clears the high of the pause, not in the middle of it. In the middle you get a worse price if you are right and no edge if you are wrong.
The stop belongs under the low of the pause, or under the last higher low if the pause is long. If the distance is so wide that the size becomes silly, skip it. Do not force the trade by moving the stop closer just to hold more shares.
A target is not a dream of ten times your money. A fair first target is a measured move the length of the pole, or simply the next obvious level. If price does not accept you within a few minutes, the break was weak. Leaving with a little, or with nothing, is allowed.
Practice on old charts before you practice with money. Find ten past examples, mark leg, pause, and trigger on each one. Then ask: do I see all three — or just a stock that is green?