I'd also like to add that if your tank is very stocked, particually if it has high waste producing fish like goldfish or pleco's or carnivorous fish etc, it is advised you should do larger water changes per week (like 40-60%) rather than 20-30% per week.
You should also clean your substrate once a week (some people do it just once every two weeks, but i personally think it is better to do it once weekly as substrate can get surprisingly dirty or stagnant in just a week)- sand can build up anerobic(sp?) bacteria and gases if it is left uncleaned or not thoroughly cleaned, while gravel can build up with trapped waste and rotting matter which can cause ammonia problems and so forth.
You don't have to buy a syphon or gravel vac to clean your substrate- netting any waste off it, then thoroughly stirring the substrate up followed by another netting and a decent size water change can be more than effective at keeping it clean if done once a week. This method seems particually good on sand as you make sure that all of the sand is properly stirred up, helping prevent anerobic bacteria or algae build up in it
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As far as filter maintanence is concerned, you should roughly clean it out in water from water changes every 1-3 weeks depending on your bioload in the tank and the filters ability to handle waste, you should clean the filter out in water from water changes rather than brand new water as new water, particually undechlorinated water, can kill off the beneficial bacteria and make the tank mini cycle. Over-cleaning the filter can also make it mini cycle, so you should just remove the worst of the muck instead of making it sparkling clean like new
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With other tank gear, you should use your once weekly tank cleaning session to check if everything else is working well and cleanly- heaters can build up with limescale, dirt or algae if left unchecked, which can effect the heaters ability to moniter the tanks temp accurately and heat it efficiently. The propellor/motor thing on filters can build up with muck as well, so if you can you should give it a quick scrub with a toothbrush or sponge.
Wiping the insides and outsides of the tank glass is good, but you should avoid using cleaning chemicals anywhere near the tank as these can have disasterous effects on the tanks water and inhabitants even in tiny quantities- you should also make sure your hands don't have any soap on them if you happen to wash them at any point during the tank cleaning for the same reason as well.
Also check your lighting- like heaters, lights can build up with limescale, algae or dirt- this isn't that bad, but it can weaken their strength which is bad if you have plants that rely heavily on your tank lights lighting to survive and thrive.
