The wheels of a skateboard are usually made of polyurethane, and come in many different sizes and shapes to suit different types of skating. Larger diameters (55–85 mm) roll faster, and move more easily over cracks in pavement and are better for transition skateboarding. Smaller diameters (48–54 mm) keep the board closer to the ground, require less force to accelerate and produce a lower center of gravity which allows for a better response time, but also make for a slower top speed and are better for street skateboarding. Wheels also are available in a variety of hardnesses usually measured on the Shore durometer "A" scale. Again like car tires, wheels range from the very soft (about Shore A 75) to the very hard (about Shore A 101). As the A scale stops at 100, any wheels labeled 101A or higher are harder, but do not use the appropriate durometer scale. Some wheel manufacturers now use the "B" or "D" scales, which have a larger and more accurate range of hardness. Modern street skaters prefer medium-sized wheels (usually 51–54 mm), as small wheels with lighter trucks can make tricks like kickflips and other flip tricks easier by keeping the center of gravity of the skateboard closer to the deck, thus making the deck easier to spin. Street wheels are harder (A 100/A 101). Vertical ramp or "vert" skating requires larger wheels (usually 55–65 mm), as it involves higher speeds. Vert wheels are also usually slightly softer (A 98/ A 99), allowing them to maintain high speed on ramps without sliding. Slalom skating requires even larger wheels (60–75 mm) to sustain the highest speeds possible. They also need to be soft and have better grip to make the tight and frequent turns in slalom racing. Even larger wheels are used in longboarding and downhill skateboarding. Sizes range from 65 mm to 100 mm. These extreme sizes of wheels almost always have cores of hard plastic that can be made thinner and lighter than a solid polyurethane wheel. They are often used by skateboard videographers as well, as the large soft wheels allow for smooth and easy movement over any terrain.
Decks come in a variety of shapes and sizes. You can choose a mini-board, a cruiser, a drop-through or a standard deck for your favorite set of wheels and hardware. Widths range too from a few inches with a 22-inch board to the wide size of a true cruiser. Some decks are flat as possible while others are significantly concave for optimized turning. You can buy a deck with artwork and grip tape already attached for a quick install or you can get a bare-bones wooden deck to truly customize.
Longboard - A longboard is similar to a cruiser in terms of overall use and getting around town. Longboards start at about 42 inches in length and about 9 inches in width. When you buy a longboard, the wheel base of the trucks is usually wider and they have wheels starting at roughly 60mm. This gives you more maneuverability and a very smooth ride.
The good news is that majority of skate shoes today come with high-quality flat soles that are capable of providing the maximum surface area designed to let you come in contact to the board, thereby promoting better control. Look for a really durable shoe, which you can wear comfortably to guarantee a safe and enjoyable experience when you are skateboarding.
To get higher ollies, I would suggesting resting your back foot on the very end of the tail and the front foot in the middle of the deck to allow for more slide. Popping as hard as you can and catching your board in the groove of the nose with you ankle practically resting in the groove will level the board out in the air. after this initial movement slide you feet back to the bolts on the tail and nose to ensure a clean landing.