Past lives have helped your soul develop to where it is now. This life right now is allowing your soul to develop, and any future lives will do the same. Past lives can't be pointless because they are your own soul history. Past, Present, and Future are all equally important. Past lives intervene with our everyday life because many of our characteristics and thought-patterns are fashioned from what happened in past lives. For instance, I'm a real warrior-type dude; I retired from football a couple of years ago and am now pursuing a professional rugby career. I love to physically battle and compete. As it turns out I've spent several lifetimes as a warrior and have fought in many battles of the past; whether they were small village battles or legendary battles that you read in textbooks. Another example: I hate frogs with a passion. I was actually killed by an arrow dipped in frog poison in a previous life. Yet another example: I don't like people being behind me, and when I go to a restaurant I like to sit where I can see everything. In a past life I was literally stabbed in the back with a knife and killed. So if you have certain little unexplainable quirks about yourself, past lives can give you insight into why you're that way now.
There are several ways, but none are easy. If you're a conscious dreamer you can gain a lot of insight simply by willing your subconscious to see into whatever you desire. People that know how to channel other entities are good sources for info in regards to yourself or anything in general. Not all psychics are legit, but the ones that are can tap into certain past lives fairly easy. I've never done the hypnotist thing, but I hear a lot of good info can flow out in a session if the hypnotist is really top notch. Or you can just meditate, and when you feel your body go numb just ask to see things you wish to see and let your consciousness take you there. It really is all about tapping into the higher consciousness because that's where all the answers reside.
And if anybody tries to mock or discredit you for trying to do this stuff, tell them to fukk off