With a 10 gallon, I would do 10% to 50% weekly, depending on how many plants you have in there. More water changed for fewer plants. Get a Home Depot 5 gallon Homer all-purpose bucket and a gravel vacuum/water siphon hose to change water with. Turn off filter and heater so you don't burn either one up when the water level drops. Siphon water out of the tank into the bucket, vacuuming the gravel by sticking the wide-mouthed end of the gravel vacuum into the gravel and moving it around, being careful not to disturb any plants` root systems. Remove and wring out/wash filter media into the bucket of dirty water, don't replace filter media unless you're using carbon or the media is falling apart - every time you replace media, you remove part of your tank's bacteria population and can cause a mini cycle.
Fill the 5G bucket to do a 50% water change, less as applicable. Remember to siphon a little less water than you fill with, to top the tank off after a week's worth of evaporation. Use the dirty tank water to water your house plants, lawn, or garden (plants LOVE dirty tank water), and then fill the empty bucket with clean tap water, and add dechlorinator (a.k.a. tap water conditioner) and any fertilizers for your plants to the new water while you fill the buckt to allow it to mix prior to adding to the tank. Use your hand to determine appoximate temperature - using your sense of touch, you can get the tank and new water within about 5 degrees of one another.
To fill the tank, DO NOT DUMP water from the bucket into the tank, the sudden change might uproot plants, shock your fish, etc. Stack things near the tank (I use two additional Homer buckets with lids and a bar chair) to get the bucket of fresh
water higher than the tank, then siphon new water into the tank. Top off the tank, turn the filter and heater back on, and you're done!
Don't use soap or detergent to clean any tank-changing hardware, as the residue can foul your tank. Just use clean water, and don't worry when the water siphon starts to change color - my siphon tube is black as midnight, but I still suck on the end to get the siphon started.