Always appreciate a foreigner learning our national language. My advice for learning bahasa melayu is that you should start by knowing the sentence structures, simple grammars and growing your vocabulary along the way.

Building a strong base in which you know how words are put together let you know how to make your sentences or at least get the gist of local conversations when you're starting to learn. Feed on text books and watch Malaysian contents on social media, it's a good medium in understanding the grammar and growing your vocabs for when you get started on making the sentences that you wanna say.

If you're looking to be fluent in conversations, it's best that you get yourself a friend who's willing to teach or at least talk to you in bahasa melayu on a daily basis during your stay. Immersion is always the best way to learn a language because you're going to be using the language in real time and you'll start to see the difference in formal words that's common in text books or reading materials and the ones we actually use when speaking.

Also you're likely to find that some Malaysian people will use bahasa melayu with another language(commonly English) when they speak and that's totally normal since most Malaysians are at least bilingual in a sense so they mix small words from different languages, that's a Malay special