The JLPT is an excellent way to get motivated to study Japanese. Being divided into 5 levels, with N5 being the lowest and N1 the highest levels, it consists of various sections, with the aim to prove the Japanese skills of the examinees. It is fully multiple-choice and since it is divided into mainly reading and listening, the best way to prepare for the test is to get familiar with the test’s structure.
Total duration varies for each level: where N5 takes only less than 2 hours (105 min.), N1 takes almost 3 hours (170 min.) and can be very exhausting.
Reading starts with 75min. at Level N5, and can take even 110 min. for N1.
At the same time, the listening time for the lowest level is only 30min., but double that time for the highest level.
The grading system is a bit peculiar: within a certain range of points for each section you pass. If overall points are high but are lower than needed in one section, than you will not pass. That way it is guaranteed, that examinees cover more or less all sections evenly.
When preparing for the test, make sure to have enough time for each part of the test: Grammar, Vocabulary, Kanji, Reading, Listening. If you know, that one section is your weak point, prepare well for it with materials specialised for that particular part, rather then studying with books which cover the whole test.
Japanese grammar, as all languages do, is well structured but, of course, has several exceptions. Learn the basics, get familiar with phrases and sentence styles. You will not need to reproduce, but need to be able to recognise the certain key points and understand their meaning.
Appropriate to your level, learn the unknown vocabulary and review them regularly.
Same goes for Chinese characters: Kanji need to be memorised. Learn their on-yomi (音読み) and kun-yomi (訓読み) and make sure to remember common combinations with other kanji.
It is usually the most difficult part, therefore reading needs careful preparation. Long texts can be demotivating, but you have to get used to it. Also, one secret advice: learn reoccurring sentence structures and composition of a text. That way you will not need to read the whole text, but can search the answers based on keywords. There is not enough time to read the text in details, so this skimming skill is crucial!
Listen to Japanese news and to basically anything available. Podcasts can be a great tool. Learn to be patient, even if you do not understand everything in the beginning.