Different species of timber will take stains differently. The most problematic species for splotchiness in my experience is pine. When I say splotchiness, I'm talking about a surface that absorbs stain more in some places than others making it look uneven.To fix splotchiness, you can either keep applying more coats to try and cover it up with opacity or sand back to wood again.To prevent it (and save yourself the pain) - I recommend applying a clear coat of 'Bare Grain,' stain, 'Natural Satin,' or 'Raw Matte' Finishing Oil as a first coat to create an evenly hydrated surface for the coloured stain to absorb into. Some of you may have sanding sealer/or wood conditioning product in your collection too which works in a similar manner.