Too feminine or too masculine

The rocket course seems to do a great job covering formal or "polite" Japanese, which seems to be fairly gender-nuetral most of the time. I am concerned though that my "polite" usage seems too feminine in casual conversation with friends. What are some things a male speaker should work on to avoid sounding too feminine, while still trying to remain polite? I don't want to make the mistake of becoming too casual in my speaking and possibly insulting someone with a masculine/casual expression at the wrong time.

well polite form is not really feminie or masculine it is just being polite, but as i noticed when i was in Japan, they dont really use polite form only in stores and hotels and stuff. When you are with friends, talk maybe a little polite if you like, but i didnt use any and they didnt mind at all.

I just got back from Japan a couple of weeks ago after spending only 10 days in country for business an, while my time there was short I was constantly in the company of my Japanese counterparts, in general I would say that the Japanese used in daily contact was very relaxed and I often would be corrected at the end of the chat as to more casual speaking terms. Though my language skills were and still are slight I managed to get by with much consideration on the part of those conversing with me. My take on the issue is that it is similar to being American and traveling to England, yes you speak english but the difference between proper english and western english is quite noticeable. The people were all very polite and overly courteous and often as eager to practice their english as was I to try out my limited Japanese.