Wheelchair use

I have used a manual wheel chair on & off for many years but I know I do not use it properly. I feel that it is only a matter of time until I will have to use it more. I do not know if there is training or if I should contact the chair supplier for help. My biggest issue is getting my hands caught between the wheels & the inner part that is connected to the wheels. I tend to catch my hands on the little metal connectors. Any assistance would be appreciated.