~snips~
Buying Low and Selling high is not bad at all, this is the simplest form of the explanations you've said. For example, you're teaching your kids math, you wouldn't teach them Calculus on the spot but you are going instead for the basic, which is 1 + 1 = 2, simple as that. Beginners can't adopt what professional traders do easily, they have to take step by step process on being a Trader they wanted to be.
Though what you have said was all true, I agree about that. On the other side of it, it would be more helpful if you're going to show some actual trading proofs (images) for them to easily understand your advice.
What the OP said reflects the right opinion, starting with a small balance will be healthier. In terms of profitability and managing risk, it is too early to expect from the novice trader to show that trading skills.
The basement idea is to buy low and sell high but applying this gold technic requires deep trading skills, risk management, market understanding. Surviving among the sharks and protecting the stop limit order from stop hunters are the second layer requirements for new traders who applied the right skills on the previous level of trading. Btw, there are a lot of trade-education platforms for learning the basics aka indicators, fundamental analysis.