If you plan to write, then I can help.
Planning involves plotting your novel from start to end, so this means, by the time you start writing, you already know the end for your novel. This may seem 'boring' or 'tedious' to pantser writers (those who don't plan much, and just write by chapter), but with proper self-discipline, routine and determination to end what you already began, you can finish what you already set out to do.
But first, the basics. You really should brush up on your English, and that includes proper use of punctuations, correct grammar, and capitalization. Don't hide behind "I'm not a native English speaker" (I'm not one as well, being a Filipino) because critics and readers can be brutal. If you can't find help here, there's always Google to help you search on the English writing rules. I mean, I committed the same mistake as you, writing before I properly learned grammar, and so I embarrassed myself with tense switching (that was back in Royal Road). I did all the things I advised you here.