Leaves can have a smooth waxy cuticle to assist in shedding water from the leaf's surfaces in wet climates. The most unwettable region of a leaf is located in the middle where gravity will help pull the water away to the leaf edges so it can drip off. Rainforest leaves often have long tapered drip tips to guide water off. Fast drying leaf surfaces discourage the growth of algae that would block the light and reduce the plant's rate of photosynthesis. If the leaf surface allowed pools to form microbes, algae or fungus would grow and damage the leaf.
Dry climate leaves often sport a dense cover of fine hairs. This gives the plant a shaded surface reducing the impact & damage from intense sunlight and protect it from chewing insects. Many plants appear silver or grey because they have so many fine hairs.
In deserts, cacti have shown extreme leaf adaptations as the leaves became vestigial structures. In the case of cacti the stem adapted to provide photosynthesis while leaves became microscopic to prevent water loss from the greater surface area leaves provide plants. Spines are adapted from vestigial leaves that no longer photosynthesized or exchanged gases so were free to perform a new function. Thick masses of fine spines shade some cacti species and stiff sharp spines protect some species. Each plant adapts from the range of genetic variation it has when the selection pressures shift when the environment and the ecology changes.
The location of leaf stomata is varied depending on the plant’s evolutionary adaptations.
Stomata are usually located on the underside of leaves. Part of the reason stomata are found on the underside is, possibly, to keep them out of direct light where there is slower air movement and less water loss in dry conditions. However I believe another valid argument for sheltered stomata is CO2 diffusion rates. Both dew and rainfall keep a leaf wet for significant portions of the year in many habitats. Further, CO2 diffuses 10^4 times slower across water than across air. If a leaf’s surface was wet the film of water would essentially block CO2 movement through the stomata drastically reducing a plant's photosynthesis. Sheltered stomata are adaptations to allow photosynthesis to continue in wet conditions as well as dry.
Some stomata are sunk in depressions, some are only on the underside of leaves while floating, water plants must have stomata on their upper surfaces to exchanges gases with the air. Plants that hold one broad leaf face flat to the sunlight have stomata only on the sheltered underface. However another strategy is found with the eucalypts with leaves that hang vertically to expose less area to the drying sun but allowing the leaves to have stomata on both faces of the leaf. They can close the stomata facing the sun but keep the other, sheltered, stomata open.
Leave’s shape, color, orientation to sun and surface texture all play a part in transpiration. Even where the leaf grows on the plant impacts transpiration. Some plants can fold their leaves on hinged petioles to bring leaves out of the light and some roll their leaves to regulate transpiration. All of these are manners plant's have adapted as they evolved to their habitat.
Leaf shape plays a part in how a plant evolves adaptations to its niche. In colder climates with winter dormant plants toothed and serrated leaf edges are much more common than in the tropics. The teeth possibly increase transpiration/gas exchange so the plant is maximally active when the temperature is greatest and light penetrates to all the young leaves of the canopy. Leaf teeth might aid with guttation where springs are cold and wet. Guttation helps keep leaves turgid and move more water than by transpiration alone. This could help unfolding/expanding the leaf and help if late freezes cause embolisms.
Compound leaves and lobed leaves have large surfaces for photosynthesis but offer less resistance to storm strength winds so they are less likely to tear. Conifer needle shaped leaves allow snow to slip through & limits the snow's build up on the whole branch. This works well with wind also slipping through the fine conifer foliage, reducing the risk of the tree being pushed over by winter storm winds.