Are you planning on writing characters by hand, or do you just intend to write using a computer or phone? If it's the latter, you only need to be able to read characters and then select them after typing their Pinyin. If it's the former, you just need to spend a lot of time practising writing out the characters. Either way, I recommend you start by memorising the most common radicals (the parts that make up a character). For example, it's much easier to remember 想 if you know the radicals (eye (目), tree (木) and heart (心)) than it is to remember it stroke by stroke.