One thing that might be of tremendous help when working to perfect your traffic pattern is selecting certain altitudes for key points in the traffic pattern. This gives a measurable aiming point and will help assure a more stabilized approach. It should be noted that these are just general guidelines that help in a standard situation. An airport with a non-standard traffic pattern, or a traffic pattern requiring extended or shortened pattern legs may require a different approach (literally!).
The AIM says that unless otherwise stated for a particular airport, 1,000 feet AGL shall be used as the standard traffic pattern altitude. During a standard downwind in a small single-engine piston airplane, the pilot should maintain this 1,000 feet AGL until abeam the touch down point or runway numbers. The pilot should plan their descent so that they arrive at about 700 feet AGL when they make their downwind to base turn. They should continue their descent to arrive at 500 feet AGL when turning base to final. This 500 feet AGL should provide a safe altitude from which the pilot can judge if they are too low or two high (the result of improper altitude control or too wide/too tight a base leg).
Remember, a good landing begins in the traffic pattern. Practice your landings and aim for consistency each time.
How many different ways have you seen a pilot enter the traffic pattern at an uncontrolled airfield? Some fly straight-in; others cross midfield and enter downwind. There are even some who fly directly into a tight base and are still rolling wings level when they touchdown. The Aeronautical Information Manual (AIM) specifies only ONE way to enter the traffic pattern at an uncontrolled airport: the 45-degree entry. This is the ONLY entry that should be used, and though the AIM is not regulatory, it is wise to follow the guidelines that it sets out.
Sure, if you are approaching an airport on the side opposite the active traffic pattern, crossing over mid-field can be a good way to enter the pattern. It keeps you from flying wide detours to position yourself for a 45-degree entry, and allows you to assess the traffic situation. But it is not a good practice to enter downwind directly from midfield, nor is it good practice to cross mid-field at the traffic pattern altitude. Instead, crossing midfield should be done about one thousand feet above traffic pattern altitude, and should be extended to a point from which a standard 45-degree entry can be made (about 3-4 miles out). Flying at traffic pattern altitude could cause a conflict with traffic already established in the pattern. Flying at only 1,500 feet (500 feet above most pattern altitudes) could cause a conflict with large or turbine-powered aircraft in the pattern, since they are advised to fly at 1,500AGL in the pattern. Because of this, flying 1,000 feet above the traffic pattern should provide better spacing for all types of traffic.
Cross mid-field and continue outbound for a few miles before making a 135-degree turn to begin your 45-degree entry to downwind. The descent may begin during the outbound portion of the mid-field crossing, or it may be during the turn to establish the 45-degree entry. Either way, it is smart to be at traffic pattern altitude by the time the airplane is on the 45-degree entry to downwind - perhaps 3 or 4 miles from the field. This will help other aircraft that are in the pattern to spot you because they will be looking for you at traffic pattern altitude. It will also help to be stabilized at the correct altitude so that there is less to deal with during the high workload period before landing.