First impressions can be misleading
I seem to be giving out suggestions from personal experience at the moment, so I’ll continue along that vein.
Today’s snippet of advice is: don’t get ahead of yourself.
You’d think it was always beneficial to have good pronunciation, but sometimes it’s actually better to make sure that native speakers know that your level isn’t quite the same as theirs (if this happens to be true). If their first impression of you is that you’re fluent when you’re not*, you will just be overloaded with lightning-speed responses that you possibly won’t understand.
If the person you’re speaking to is made aware that perhaps you aren’t quite as proficient as they are, they will be more likely to grade their language and slow their speech a little. It’s much better to be able to understand all or most of the conversation and be able to respond than to miss everything because of speed or local dialect.
So, if you know how to ask a question in a contracted or colloquial way, make sure that you will also be able to predict and understand the answer!
Similarly, maintain a comfortable and steady pace. If you can say some sentences very quickly, but stumble on others, it will make the conversation much more difficult for the listener. A steady rhythm will ensure you say your words correctly, and will give the listener an idea of how quickly to provide their responses.
*I’ve had endless experiences with this kind of thing in Asia. I always try to learn a few pleasantries in the local language, but because I sometimes look like I could be a local myself, I get torrents of Thai, Vietnamese, and Mandarin in response. I’m glad most people are accepting of my blank looks and stilted apologies.