This is not investment advice.

Mistakes that I did so far:

• once I have identified good company and good technical entry setup I did not create large enough position
• once trend has reversed to an uptrend, I just did initial position and was not adding regularly while stock was still in uptrend
• watching only stocks that are already on my watchlist
• was waiting for ideal technical trading/buying setup, but these rarely come
• thinking that successful companies are too expensive, especially the tech ones. Of course we might be in a tech bubble, but technology is present in every aspect of daily lives and is becoming more and more dominant.
• thinking that tech companies are just tech, but for example Google is more like advertisement company heavily leveraging tech. Or Netflix is movie entertainment leveraging cloud and streaming. Every tech company has similar story, the point is that tech companies are having economies of scale and can expand super easily and cheaply.
• good companies can grow constantly over 20-30 years (with occasional drops of course), so they are not really expensive in many cases. Plus market prices in growth for several years ahead.
• when I really like company products and Im using them a lot or I'm loyal customer for years. Then I should buy the stock as well (missed big on AMD, but was buyng their products for 10 years)
• stocks (and crypto) move in trends and it takes a while to reverse that trend, so buyng on downtrend can be very risky
• downtrending stocks heve either 'V' shaped recovery (often weekly RSI low) or have some kind of double triple bottom, so these might be good time going long

What I did just fine:

• successfully avoided adding to investing positions on long term downtrends. For this, 50 day EMA is very useful
• kept enough reserves for a cese of significant market drop, this helps tremendously with decision making during turbulent times
• I dont generally take short positions, these have potentially unlimited loss
• kept funds ready to deploy

Lessons learned:

• times of crysis accelerate innovation
• strong companies come out of general crysis even stronger, since they buy all the distressed companies during recession, so every recession makes big companies stronger
• when there is good setup, entry position in small increments, but very frequently, almost daily and ride the trend
• ETF funds are typically weighted heavier towards stronger companies, buying them will make sure I have larger positions in the big companies
• mutual/actively managed funds are good for nige areas - disruptive technology, genomic research, general biotech, artifficial intelligence/robotics
• buy business with moat/competitive advantage that is hard to overcome. Example buying airport stocks instead airlines.