Use what other traders use:

In a perfect world, every trader would be looking at a 14 day RSI and making trading decisions based on that. If that was the case, when RSI would go under the 30 level, everyone would buy and by consequence the price would rise. Needless to say, the world is not perfect and not all market participants follow the same technical indicators, draw the same trendlines and identify the same support & resistance levels. The great diversity of opinions and techniques used translates directly into price diversity. Traders however have a tendency to use a limited variety of technical tools. The most common are 9 and 14 day RSI, obvious trendlines and support levels, fibonnacci retracement, MACD and 9, 20 & 40 day exponential moving averages. The closer you get to what most traders are looking at, the more precise your estimations will be. The reason for this is simple arithmetic, larger numbers of buyers than sellers at a certain price will move the market up from that price and vice-versa.