Still: a heavy plant load helps with your bioload a LOT.
For a basic guide, look for filters for the number of gallons you have, determine if your fish/plants need a stronger or gentler flow, and look at the pros and cons of different filter types (hang on back filters, cannisters, under gravel, etc). If you have low fish stock and/or a heavy plant load, you might be able to get away with no filter with a good water testing regimen. But definitely wouldn't recommend that for beginners. Still: a heavy plant load helps with your bioload a LOT.