S and R are one of the most fundamentally sound indicators you can use. They 'work' because everyone trading that stock sees the same area and tend to think the same. The key is to buy during the swing up back to the resistance area to get in before a potential breakout and not buy at the 'top'. Or after the R break on a pullback. Opposite for shorting. I draw my trendlines in blue for daily resistance and white on the intraday chart. Helps me see what trendline is from what timeframe.

@Palmer Is multi month support/resistance more important than daily resistance or should I be doing a mix of both?

I would definitely check both. The longer term the resistance the more powerful (stronger) the breakout can be = buy or the more stubborn the price action can be = sell. Longer term (monthly) support and resistance is critical. Think of support and resistance as 'areas' of price action and not exact price. In other words,

if there is intraday or even montly resistance of a given stock say at 4.35...give some +/- on both sides of 4.35.