In this video we look at inclined chaturanga push ups. Practicing these will help you increase strength in the chest and triceps regions. Make sure you feel comfortable. If you feel any pain you should take a break. Using blocks helps my wrists feel better. Blocks also help to put my shoulders into external rotation - which helps to open my heart (thoracic extension).
Remember you want to have a neutral spine; and most importantly you want to respect your body whether it's telling you it's tired or injured you should listen to it.