Body odor is caused by the effect of skin bacteria on sweat.  If you have a body-odor problem make sure is the odor problem real or just your imagination? (ask a trusted friend to confirm)
Shower regularly, 2 -3 times a day.
Change clothes regularly, wear clothes which are washed & clean. Make sure clothes are properly regularly.
Use "antibacterial" soap as far as possible
Use anti-perspirant under your armpits after a bath. Your pharmacist can give you advice for stronger ones.
Sometimes, poorly washed clothes or clothes which aren't dried properly can be a cause. Wash & dry them well to help eliminate body odor.
Watch your diet and see if eliminating suspect foods might help.
Consult your doctor if nothing else works, it may be due to an illness