These "tricks" you've listed really aren't "tricks", they're pretty much just generic trading advice. Not to mention these "tricks" shouldn't apply to every situation. It hugely depends in many factors.
2. Now look into market, if you think you are in profit then book your profit and wait for dip, but if you are in loss then wait some more time for more dip and pick some more coins.
Just automatically selling after you've seen you've gained profit isn't always the best thing to do. Sometimes it's better to ride out the wave up, wait it out, and sell after a slight dip. Again, it depends on many factors.
3. now if you see market dip more and more, then wait and wait for best time and buy for further 300$. By this way you can balance your high purchase with low purchase because at some moment it will pump if you think you invest in good project.
If you have $300 left, it isn't preferrable to go all in with the $300 on a certain price point. most of the time it's better to apply Dollar-Cost Averaging
[1] all the way down, as there's no way for us to know if your price target is the bottom or not.
[1]
https://www.investopedia.com/terms/d/dollarcostaveraging.asp