Setting limits before the first ball
Decide the total in August, not during a chase in September, and use the tools operators are obliged to give you.
The decision that matters most gets made before the tournament starts, in a calm moment, and it is not which team to back. It is how much this entire competition is allowed to cost you.
That framing is deliberate. Deciding a total in advance turns thirteen days of individual choices into one considered choice, made when nothing is on the line. Deciding during a tournament means deciding while a chase is going badly, which is precisely when human judgement is at its worst and when the reasoning always sounds sensible. Betting is entertainment with a real risk of loss, and the sane way to treat entertainment is to budget for it the same way you would budget for a season ticket or a fortnight of nights out. The money is spent when you decide to spend it. Whether some of it comes back is a separate question, and not one you should plan around.
Consistency of stake is the next piece, and it is quietly the most important. Someone staking the same amount on every selection knows what their exposure is. Someone who stakes a little on the games they are unsure about and a lot on the ones they feel strongly about has, without noticing, made their overall result depend almost entirely on how their confidence happens to be calibrated. Confidence is not evidence. A steady stake also makes the arithmetic legible, which matters because the alternative is a vague sense of roughly breaking even that is almost always wrong.
Then there is the behaviour that turns a hobby into a problem, and it has one name: chasing. Increasing stakes to recover a loss feels like a correction and functions as an accelerant. It is the specific mechanism by which manageable losses become unmanageable ones, and it does not require any unusual recklessness, only a bad evening and a reasonable-sounding thought. If you notice yourself calculating what stake would get you back to even, that calculation is the signal. Not the losses.
The useful thing is that you do not have to police this on willpower, because regulated operators are required to provide tools that do it for you. Deposit limits cap what can go in over a day, week or month, and they take effect immediately when you tighten them while typically imposing a cooling-off delay when you loosen them, which is exactly the asymmetry you want. Loss limits and session time limits work similarly. Reality checks interrupt play at an interval you choose. Self-exclusion locks the account for a fixed period or permanently, and a properly run operator will not let you reverse it on impulse.
Set these on the day the account opens, before there is any reason to. A limit chosen in advance is a decision by the version of you that was thinking clearly. A limit you go looking for in the middle of September is a decision by the version that already needs one, and that version will negotiate.
If betting has stopped being entertainment, stop and contact a licensed support service in your country. That is a better use of an evening than any market on this site.
The short version
If betting has stopped being entertainment, stop and contact a licensed support service in your country.