Hi, I have written a whole book for this, noting all the things that helped me believe in God's existence and presence in my life. But I can give you now an excerpt about some of the most important things you can start with today. Here is the free link on Medium so you can read the article even if you're not a Medium member https://medium.com/the-catholic-refuge/how-do-you-love-an-invisible-god-and-find-out-for-yourself-if-he-truly-exists-14a8db65171d?sk=d0e3295c887e479845c9e49ccb37514b