The same happens to me when I learn English, the use of prepositions are very difficult and I always try remembering and understanding them with verbs and short sentences. Although I'm still on my way, it works very well for me, for example...TO GET, get on/off the train, I got it, to get up early, etc. I think only learning all the particles doesn't help you, learning HOW TO USE them is needed so, please learn and understand them with short sentences, then you can make long sentences step by step with the correct particles. It's only my opinion. I hope this was helpful.

Honestly, the best way to get familiar and comfortable with them is to just see tons and tons of example sentences and pick them apart and understand why each particle is used in each context. That being said, it really comes with experience, so don't fret it too much, as long as you have the basic understanding. I still have the occasional slip up myself, but am often able to quickly identify and correct it during conversation. We can go over some specific examples if you have any.

I also recommend Tae Kim's Guide as TonyH said. If you still don't understand I recommend imabi.net although you'll need to have a bit more understanding of Japanese in terms of vocab. If that doesn't help you then I agree with Ryoko. Some things you won't actually understand until you use them, particles are rather abstract just as particles in English are. There is no one to one translation of particles from one language to another, some times it's better just to get the feel of things. With that being said I'll give you some tips of how I remember the particles to be. Don't take my meanings to heart, learn and FEEL them yourself. は = "As for" in english. A subject marker. が = Similar to は although is less broad. It specifies something. で = think of this as "via" in english も = "too" in english に = indicates a movement. の = possession. Also makes things more narrow. If you think in English, cat's hand is taking the word "cat" and making it more narrow by adding the word "hand" Just like weed, just feel, you don't have to fully understand it, if you just feel it, it's k.