dongding oolong has a very diverse range of oxidation so does tie guan yin.
generally autumn and winter dongdings are very lightly oxidised, just like a baozhong tea or even lighter sometimes.
else lower altitudes and grades of dongdings can also be toasted to give Tan Pei Oolong tea, which is a lot higher in oxidation.
Tie Guan Yin has a large variety of oxidation, high grades of TGY are often lesser than mid oxidation, preserving the natural fragrances, a yellowish brew, nuances that could be lost or overwhelmed by higher oxidation levels.
i suggest about 4-5 grams of tea leaves to be put into a small gaiwan, of about 100-150ml, washing the leaves for 2 seconds and draining the water away, and infuse for the next 15 seconds, and decanting into a drinking cup. this can be repeated many times extending the steeping times by 5-10 seconds. dongding is quite mild a tea, using more leave and shorter brewing time in less water will give a rich flavoursome brew, with the best fragrance and texture in the second/third brews.
you can brew it in tea pots, but do not infuse for too long. high mountain tea leaves are very lightly oxidised and tender green. high temperatures for a few minutes will end up giving you a vegetable soup, which tastes pretty terrible.
just like good green tea, short infusions of good leave quantity gives great flavour. but when poorly infused, with high temps for long periods of time, it becomes so medicinally bitter and the delicate scents and fragrances are lost.
there are varieties of high mountain oolongs that can be infused in boiling water and for longer periods of time, i.e. more highly oxidised teas, slightly mediocre grades. a small 2.5 gram tea bag can flavour a larger amount of water, without the true quality of a higher grade