Backwoodsmanship has always been a part of Guiding, and over the years, many different styles of shelter have been suggested, depending on the materials available in the given era.
When planning to build a shelter, the first thing to consider is the site, and the possibilities it offers. Is there a water source in easy range, from which you could draw water to sterilise? Is there flat ground? Are there natural features offering shelter you can adapt - large bushes or shrubs, a wall you can build a lean-to shelter against, a cave or hollow you can use? A tree with a cross-branch you could hang a shelter from? Is it close to paths (which could attract passers-by) or is it secluded? Then look at what sort of materials you have - both any you have with you, and any which are available naturally. Are there branches you can lash together? Are there materials like bracken which you can attach to provide insulation and waterproofing? Also consider the size you need the shelter to be - how many people is it to house, and is it to sit in, or to sleep?
If there isn't natural shelter which you can adapt to roof or add walls to, then you will have to build a structure from scratch. In this case, it becomes important to consider what size and shape you need the shelter to be, and to work out how you can create a secure, stable structure. This can be by creating a ring of twigs which is secured in the middle (like picture VIII), creating an upright roof with shelter suspended to either side, as in picture XVI or IX, or by using springy twigs to create a tunnel shape, as in picture XIV. In terms of shape, if it is to be an overnight shelter then you want a long narrow shape which you can sleep under, but the roof doesn't need to be very high at all. If you will only be using it as a day shelter to sit in, then it can have a more compact footprint, but will need to be a little higher so you can sit upright. This has to be considered in your design planning.
If you have access to tarpaulins then they can be laced together to give you shelter - try to avoid having the seam right on the top ridge of the shelter, and ensure the tarpaulins are overlapped and laced together to avoid leaks. If not then you will need to look at 'thatching' your shelter with foliage to give some rain shelter. If using boughs or batches of leaves like bracken to thatch, hang them with the root at the top and the leaves or fronds hanging down, so that rain landing on them naturally runs downwards. Once the basic structure is constructed, you can start to think about adding to the comfort. The floor can be padded by using long grass, heather or such to make it more comfortable to sit or lie on, especially if the ground may be damp or muddy.
Whenever you build a shelter, as part of your early planning, plan how you will deconstruct it and return the area to at least as neat a condition as you inherited it, if not better. Make sure all non-natural materials, such as string or plastic, are 100% removed from the site. If you have lit a fire, nobody should realise, with no giveaway clues present.