Just a few simple things to keep in mind .. in suggested order :)
Greet
Use smileys often
Thank for every help
Ask precise questions and wait for answers
Appreciate them for any positives they have
Try to explain reasons/purpose for asking for things from the person
Use words like we rather than you or he or she. If you have to, use names - politely.
After a couple of talks - practise small talk. Small talk includes talking about anything but work like wheather, a news etc.
Try getting casual
Don't forget to greet while leaving
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