OK, ck1, 500X s enough to see blood cells, the way to make them easy to see is to place a drop of blood on end of a clean slide then use the end of another to drag the blood along the slide so that you get a very thin film of blood. Ths will dry quite quickly so can be easily handled for viewing. Be careful when using maximum power not to wind the objective lens through the slide. To avoid doing this carefully lower the oblective towards the slide whilst watching the clearance as it approaches near zero, then wind it slowly away whilst looking through the eyepiece for the moment of focus.