I prefer to buy stocks with agreeable financials and technicals. On a larger time frame, ideally the stock is not too far along in its move. A price run that has gone for too long, probably is ready to drop, unless the stock is strong.
After making a decision to buy a stock, I prefer buying stocks at the end of the day, ideally just before market close. After a full day or week of market activity, viewed in the larger market context, a person should have enough ideas to place bets before the next session. Why ponder things overnight? If you are truly confident about a stock, do not fiddle with pennies on your bid. I've missed many stocks buys with low offers.
If the broad market moves strong and higher for three days, I'll avoid new stock purchases on the fourth day. I can wait. When the market moves consecutively lower, I look for support levels to hold before buying.
I start buying one-third of a position and evaluate the purchase for a week at most. If I am wrong, I to exit before losing too much. If the stock moves higher, I buy more when it enters a new trading range or makes a big move on volume. Adding appropriately should multiply gains and reinforce good decisions.