When you are starting out with lucid dreaming, doing frequent reality checks is probably a good idea. As to how often, the answer is simple: whenever you remember them or something triggers you to do it, e.g. discussing dreams. If you don’t remember them during the day, then analyze your dream journal entries for dream signs and try to program yourself to RC as you encounter those things.
There are tons of different ways to do reality checks. You can read about them on the internet or just here on the forums.
What is your favorite reality check?
RC FAQ - Reality Check
Pick one that you like and that is easy to incorporate into your everyday life. Also imagine yourself doing them in the dream. Try many of them and narrow it down once you have more experience. What’s really important in the end is your final question:
No matter how you’re doing them, they will have a positive effect. But the extend of the their benefit varies greatly depending on how you perform them, and this is the main issue with reality checks.
Most lucid dreaming tutorials, explanations and guides introduce them as a simple tool to attain lucidity. In order to introduce the concept of lucid dreams to the uninitiated this is fine. But if you’re serious about becoming a lucid dreamer, I think it is vital to understand that the RC is not really a tool but more of a metaphor. What matters most about them is the intent to properly discern reality from dream/virtuality. Once you develop this skill, you can awake inside your dream by realization. And then RCs become a tool that you can use inside the dream to increase certainty of the dreaming state.
But while you are awake, the concept behind it is more important than the method and what it’s doing for you.