Check the weather conditions
You can sleep under the sky if the weather is good. Take a sleeping bag and pad with you or make use of natural things such as grass and leaves to make a comfortable bed. Sleep on the bag and wake up to a lovely sunrise early the next morning. Use some tarp to make a shelter in order to stay safe from rain. Erect the tarp or tie it to a tree or some branches with the help of a rope or hiking poles. Put it on high ground so that water does not gather near your sleeping bag.
You can use a light weight bivouac sack instead of a regular tent. This is a small shelter that will offer protection to your sleeping bag. It is usually waterproof and provides excellent insulation to your sleeping bag. Make sure you know that it is a good option but it cannot be used by people who suffer from claustrophobia.
Sleeping in a hammock is another alternative as it is allows you rest without touching the surface. Some are waterproof and come with bug netting to protect you from insects while you sleep. When using a hammock you need two solid holding points in order to hang it but they can be used like a bivouac on the surface as well. In addition, you can light a fire to stay warm while camping. Putting heated rocks below your bed is also effective in cold weather. Try to sleep in a wildlife free zone and also stay away from berry bushes and other food sources.