The maximum amount of money you should invest on betting is money that you can afford to lose, without your standard of living and peace of mind being affected.
Choose one or several tipsters that fit your profile: benefits, hours, volatility, duration of odds, etc. THE DIVERSIFICATION OF THE RISK IS FUNDAMENTAL: As you increase the number of tipsters you are subscribed to, the risk decreases, since it is statistically very unlikely that all of them will accumulate losses or bad streaks at the same time.
Once you hire a tipster, you must define the value of your unit. At most it should be your bank divided by 100. Once you have defined your unit, you have to stick to the stakes of the tipster. Never bet more than 5% of your bank in one single bet.
If you are a novice, consider the goal of the first month to simply recover the amount paid for the service. The first month will help you to get familiar with the tipster, learn the betting jargon and get better at fetching odds and make the bets quickly and without errors. It is not unreasonable to bet amounts between 1 and 5 € to begin with and to get used to this.
Do not increase your stake unit value until your bank grows and acquires a certain cushion.
Do not pretend to do things similar to what you think the tipster does. Probably, if you do not analyse the games for about 40-45 hours a week, you will lose in the long term.
Do not bet on picks later if the game and odds conditions have changed. It is preferable to let it go and wait for the next pick.
Do not be afraid of losing streaks. It is possible that a tipster fails several consecutive forecasts, and this is not necessarily due to the tipster selecting worthless forecasts.
Keep an eye on the accounting of your picks and follow the evolution of the service periodically.
Meditate all decisions rationally. Do not be impulsive.