Odds are a price, not a prediction
Decimal odds show the total return for a winning stake, including the stake itself. They can change before a bet is accepted, especially in live markets. A price moving in either direction does not make a result certain.
Read the settlement rule
Each market has its own conditions. Check the rules for postponed or abandoned events, overtime, penalty shoot-outs, player markets, and errors in displayed odds. Cash-out, if offered, is optional and can be removed at any time.
Keep the maths simple
Set your stake before opening the bet slip, confirm the accepted price, and treat the amount staked as spent entertainment money. Do not use odds calculators or multi-bets to justify a bigger risk than your budget allows.