Be patient with your strumming. Take it slow. The way I started is to take each chord...say G-C-D. And then strum each chord 3 times nice and gently so it rings true. If you can do this for these 3 chords and strum it 3 times and have it consistently sound true you should be good to go. Fingering must be correct or it wil sound screwey.

You could also make the chord and pluck one string at a time to make sure you are pressing correctly. Not sure if you are doing open or barre chords. Barre chords are tougher. It just takes practice. Ive been practicing my bar chords for 3 months and just now are they starting to sound solid. Very choppy in the beginning. This stuff takes time, it doesnt happen over night.