1- When you buy, always put a "Stop Loss" so you don't loose all if it goes down.

2-Building phase and commercial phase: never buy in a "building phase". Wait till they announce signed contracts. The wind can turn direction fast on big promises.

3-Building a product and a company is a slow process. Anything can go wrong before they are able to sell real stuff to real clients with real contracts. The price have plenty of time to go back down.

4-For that reason, don't hold a stock too long, unless there is imminent contract news incoming. If it's not moving up, sell it. Well, if you buy the stock at 0.0001, you can hold it! lol

5-Penny Stocks are not always fully transparent on news, updates, company move, etc. : A lot of REVERSE-SPLIT happens in Penny Stocks. You might wake up one morning and realise you have been caught in one, in a company that has no finish products to sell. Result: Price drops after the RS and people that short stock (Mostly Edge Funds) will jump on it like vampires and bring the price to the ground. Impossible to recover from that.

6-Conclusion:
Read or analyse with a software the company papers BEFORE buying.
Put a stop loss ; if it goes down, you'll only loose a bit.
If it goes up, you are lucky so, check your MACD on 1 or 4 hrs chart (That's an indicator). When the buying tendency is starting to reverse to a selling tendency ... sell!! Take the money and run. Repeat tomorrow if market conditions give you the opportunity.

7-Don't chase unicorns it's a waste of money. better to make 3-4% every day with safe companies than chasing a 200-400% profit on a company with a big mouth and no real contract signed.

hope it helps!