I don't think there will be a lot of signs to tell you when a dip is coming. It might be caused by news, which can be random, or it might just happen randomly because the pool of new bitcoin investors is drying up. If you are going to make a bitcoin trade, you should base it on fundamentals and make it a long term trade.
Yeah. In a way, you can know if a market is trying to switch trends, but you cannot say if it is going to be a huge dip or a small correction until it happens anyway. Indicators and analysis are there for reasons and that is what one can always use to try to make market decisions to one's favor.
One cannot always get it right all the time, but most of the time, you definitely will. It only takes some level of knowledge and experience to able to make use of those analysis to your advantage for a buying or selling position. Also, a dip or downtrend as the case may be will not just happen once, it takes time unless for a pump and dump market.