We recommend betting the same amount of money on every game, which is known as a flat-betting approach. You should be using anywhere from 2-5% of your starting bankroll for each play, which ensures that you can sustain any hot or cold streaks you may encounter. People who fluctuate their unit size or bet several units on one game are more likely to lose their bankroll in a short amount of time.
For example, if you start by depositing $1,000 in your bank account, you should be betting somewhere between $20 and $50 a game depending on how aggressive you want to be. After an extended period of time, you can reassess your situation and change your unit size depending on how you're doing. You shouldn't do this frequently, as a big winning or losing streak during a short amount of time is likely due to random variance rather than your actual betting skills.