Here goes my own guideline for account management (not just margin management). It has been long-term working for me but may not be suitable for yourself.
I try to not put at risk more than 10% of my account on any one trade.
For example, let’s say I start with $5,000 in my account. Which means that for any trade I look at, I do not want to risk more than $500. (Mostly I risk way less than that.) I have to plan my entry and SL placement so that if the trade goes against me, I can exit without losing more than $500.
Sometimes a market will move so fast against you that you cannot escape according to your plan, but on balance it should work out.
If you ignore margin for a moment, you can see that this will give you at least 10 trades to work with. If you have been practicing your system through solid paper trading routine and are confident enough to trade with real money, 10 losing trades in a row should be a rare thing. The $500 limit keeps me away from those kind of trades where the market typically moves far more than that, but that’s OK with me.
As there’s no requirement to trade. Being patient like the hawk until the trade shows itself to me.
Also, the smaller your account, the fewer markets you can trade because of margin requirements, but there still will be plenty of opportunity for you.
You’ll have to experiment with conventional account management strategies to find your own comfort level but you MUST do it. Trading is like any other business. Your first goal must be to STAY IN biz. You cannot (and will not) succeed if you are out of the game, right?
Best of Luck to all.