Which timeframe to look for a strong trend?

to spot a strong trend, should we look up for 1hr, 4hr, 8hr or 1 day timeframe?

Slow Stochastics
if 1hr timeframe is saying overbought
4hr timeframe is saying oversold.

How do know if it is a strong downtrend or uptrend?

As a rule of thumb, if prices are above/below 30 week or 40 week simple moving average, you most likely have a trend, but it all depends on what timeframce you are trading. By the looks of it, you really don't know what you are doing, find and EGDE!

Find a time frame that suits your lifestyle and personality. If you have a day job then 4 hour and daily would probably best. In fact if you are just starting out then I would not trade any lower than this to begin with.

Just concentrate on the trend on the time frame you intend to trade with and if necessary check the time frame above if needed but don't over analyse every time frame because you will just get confused.

yeah just like what willf said, find a time frame that suits you and the way that you trade, you don't have to adjust to a certain time frame if you know what i mean, then when you hit you comfort zone you will realize how more convenient it is for you best of luck!