I started lifting to lose weight. I felt I was making progress, but I just weighed myself for the first time in a month and found I have actually gained weight. What am I doing wrong?
The only mistake you are making is letting the scale dictate how well you are doing. Muscle weighs more than fat, so if you are training hard you should expect to gain weight in the form of muscle. Even though you are gaining weight, you are most likely looking better overall. Focus on what the mirror shows. If you are looking better and you are leaner, that is a positive result. You are swapping fat for muscle, proof that your program is working.