Try to read all of these, and if you want to know the meaning of a word, you can go to http://jisho.org and look it up. Sometimes there's also a "Play audio" button so you can listen to the correct pronunciation (very important).
ひらがな と カタカナ (かたかな)
It is simple memorization. Read them often, and write them often. Also use a list with simple words written only in the script you're learning and try to read them out loud. You don't have to learn for a long period of time, but you should try to learn every day, so that you don't start to forget the things you went over the day before.
Here are some simple Japanese words written with only Hiragana that you can try to read. First I use only the vowels, then I add the か row, then the さ row etc. so it gets more difficult gradually
I learned them by getting a free app that shows you how to write the strokes (animated). I wrote it repetitively, maybe like 4-5 lines of each character on a paper. I did it in chunks every day, but also went over everything I had learned too.
As others have said it is mostly a memorisation thing, you just have to do it lots.
What helped stick it in my brain though was also trying to write japanese words with the kana, or writing sentences that I already knew, so I could put them into practice.
Along with this I used this cool site which has a fun game for both hiragana and katakana: http://www.csus.edu/indiv/s/sheaa/projects/genki/hiragana-timer.html
A great way to learn the hiragana, katakana and kanji is through context. It may be helpful to find pictures to associate with words that begin with each hiragana character. I think most people pick up hiragana rather quickly, katakana is a little more of a challenge for some reason and then of course kanji is the hardest.
I recommend karaoke to you. With karaoke, you'll be forced to learn how to read the kana and kanji (with furigana) faster, plus you'll be exposed to more vocabulary. When I started studying for JLPT, I was amazed at how much of the JLPT vocab and grammar were used in song lyrics and because of JLPT I noticed them more and more.
Whatever method you choose, you should read and write daily to get more used to the language. If you study a little each day, you'll be amazed at how quickly the characters sink in to your memory. Also don't be afraid to pick up a book. I learned to read and understand more by reading manga and eventually novels. With the novels, I wrote the furigana over kanji I didn't know and wrote the english definition next to vocab I didn't understand.
Hope these tips help you on your way to becoming proficient in Nihongo. がんばれ！