The legs on the washer are adjustable, the rear legs are often (not always) self-adjusting, make sure washer legs are not stuck and that they can move freely. But the front legs can screw in and out to move the washer depending on the floor the washer is sitting on. Make sure the washer is as low to the floor as possible. When the legs are screwed out too far the washer becomes wobbly. Often on the metal style legs there are lock nuts that can be tightened to secure the legs so they don't move on you. Washers where really meant to sit on a cement floor, if your washer is on a wooden floor look carefully at the strength of the floor. If the floor is moving up and down when the washer is running, the floor may not be strong enough to support the washer's weight. Most main floor laundry room's floors are nailed down; the sub-floor is more secure if the sub-floor has been screwed down. Sometimes extra support may have to be added under the flooring to add some strength. Especially with Front Loading laundry, the additional weight is tough for older home's floors to accomodate.

Check water fill hoses for cracks, blisters, corroded fittings and leaks. Cracks are a sign of aging and a breakdown of the rubber. Blisters signal a rupture in the inner lining of the hose, which means the hose may burst at any time. Corroded fittings mean the hose has leaked or is leaking now. If you don't replace the hose, you may find the corroded fitting is virtually impossible to remove from the faucet when you need to remove it. Replace the hoses if they have any of these conditions. ( water fill hoses generally need to be replaced every three to five years, regardless of whether there is a visible defect.)

Make sure the dryer is not pushed back against the rear exhaust duct causing an airflow restriction. Pull the dryer out away from the wall. Unhook the vent from the dryer completely. Do not put anything over the dryer exhaust on the back of the dryer. Do a normal load with the vent unhooked. If it dries better or ok like this then the problem is in the dryer venting. Like a blocked vent pipe or a smashed or restricted vent hose.
 
If the vent doesn't make a difference, then check the blower wheel for excessive lint builds up, DO NOT TRY WHILE DRYER IS RUNNING. Check that there isn't anything stuck to the air intake baffle inside the drum, (i.e. the screen on the back wall of the dryer when looking into the drum). Check the lint filter chute for blockage.

Never overload the dryer.
When drying only one or two items, toss in a few items of varying size to promote good tumbling action and improve drying results. Dryers with an Auto-Dry cycle will not dry properly with a very small load in the tumbler.
 
Never use white plastic exhaust duct on any dryer!! The stuff is flammable, and unsafe on any dryer!