我要去...

Just drop a destination right after the phrase. No prepositions like 'to' are needed in Chinese. If you want to go to the park, say 我要去公园. If you're heading to the office, it's 我要去办公室. It’s like a LEGO set where you just snap the place onto the end. You can also add a time at the very beginning. For example, 明天我要去北京 means 'Tomorrow I'm going to Beijing.'

Use it when you are physically leaving a room. Use it when planning a trip with friends. It’s perfect for telling a taxi driver where you want to go. You can also use it in a text to tell someone you're on your way. It works at the office when heading to a meeting. It even works when you're just heading to the bathroom at a party.

Don't use it if you are already there. That sounds a bit like time-traveler confusion. Avoid using it if you are asking for permission from a strict boss. In that case, 我想去 (I would like to go) is softer. Also, don't use it for actions that don't involve a location. You wouldn't say 我要去吃 (I want to go eat) without a place. Just say 我要去餐厅 (I want to go to the restaurant).

Chinese culture is often very direct about daily plans. Asking 'Where are you going?' is a common greeting, like 'How are you?'. Responding with 我要去... is the natural, polite way to answer. It shows you are a person with a purpose! In big cities like Shanghai, people are always on the move. You'll hear this phrase shouted into phones on every street corner.

If you want to sound more casual, you can just say 我去.... It drops the 'want' and becomes 'I'm going to...'. If you are undecided and just dreaming, use 我想去. That adds a layer of 'I'm thinking about it.' For a very firm 'I must go,' you might hear 我得去. But for 90% of your life, the standard 我要去 is your best friend.