As a casual woodworker, I think I am a fair woodworker when it comes to creative design, precision machining and quality assembly. My weakness is wood finishing.
I joke around with my family and friends by telling them that I make sure my wife gets to admire my assembled projects “before I ruin them” , meaning “before I stain & finish them”. Now, while I would like to think I am not that inept, I definitely do feel that staining and finishing is often the most critical part of completing my woodworking projects successfully.
What I have found to be important to get good finishing results is to select wood that stains evenly. My personal favorite is Oak. Soft woods like Pine require a lot more pre-stain work and generally cause me problems even if I use a pre-stain conditioner. I also have learned the hard way that very careful pre-stain sanding (especially end grain) and very thorough removal of glue from wood surfaces prior to staining is critical. Taking the time and care to do the finishing job correctly is a huge factor in how the finished project will look.
There are numerous great publications available (Understanding Wood Finishing by Bob Flexner, Flexner on Finishing: Answers to your finishing fears and frustrations by Bob Flexner, Tauntons Complete Illustrated Guide to Wood Finishing by Jeff and Susan Jewitt, and Great Wood Finishes by Jeff Jewitt) on wood finishing and well worth the investment in time to learn as much as possible from experts. Armed with knowledge and practicing patience, even I end up having respectable wood finishing results.