Over the years, I've seen many people stumble over the question as to what is psychic information and what is the product of their own psyche. It is a hard skill to learn on your own. Attempting to tell if that twinge in the pit of your stomach is actual premonition of doom regarding the Big Thing you are attempting to do or if it is a case of digestive discomfort due to anxiety is not easy. You can spot the people who are early on the road of practicing divination because they'll attribute pretty much everything to psychic causes. They're so excitedly looking for signs that they'll declare 95% of the things they stumble over to be just that.
When I was starting out in doing intentional divination, I had some days like that. (Alright, more than 'some' but I was a kid and I have a highly active imagination. I self sniped on this one many times.) It took some time but I learned to recognize the difference between anxiety and premonition, most of the time. And I also learned how to filter out what was the product of my over thinking everything and what was psychic input. Some people would say this is a skill that can only be learned over a long period of study and practice. I don't agree with it. I think that given six months of focused effort, a beginner psychic can learn to pick up on these differences.
There is no big book of techniques I can point you to. (Though I have started work on writing a handbook that covers general information about psychic stuff. It is going to take me a while to get the first draft written. It is hard because I have a LOT of information to sort through.) There are two reasons why there is no standard set of techniques. First, there is as many different ways to experience psychic phenomena as there are people. At best, you can get some guidelines for different processes that can invoke the phenomena and some general information about the most common, publicly discussed variants. All of our brains are wired differently and we're going to see everything from slightly different perspectives. These differences are significant when you start looking at the architecture of one's inner self.
Second, the different systems for analyzing psychic phenomena are all highly varied. Attempting to create a uniform system that covers everything is a fool's errand because no matter how much you think you have covered, there is going to be things that you didn't include because you weren't aware of them. There simply is too much going on to turn it into a single structure. It is only marginally less complex than the natural systems that have given rise to human thought. It is best to keep an open mind and be willing to learn as much as you can while you go forward.
The biggest thing to keep in mind when it comes to psychic stuff is the fact that there is going to be a significant percentage of the time where you are just going to have it wrong. There is going to be a time where you are going to misread the portents. There is going to be a time where you are going to fail to recognize the signs before you. And there are going to be times where the information you see just does not fit anything you understand. Any psychic who claims their success rate is in the range of 80+ % of the time, you should view them with suspicion.
The really good, really experienced psychics that I know hit a positive result on their efforts somewhere between 2/3rds of the time and 3/4ths of the time. These are people who have been engaged in the exercise of psychic skills and gifts since they were very small. They work on their skills daily and have a great deal of study into their work as well. Accepting that you will get it wrong is a mark of maturity and it also allows you the room to continue to grow in your skills. On the whole, when you are at work with psychic skills, take the time to stop and assess what information you discover. Keep in mind that sometimes that random sign you see has no meaning beyond the fact that it is just what it presents itself as.