Can't do it all

There is a lot to marketing.

Branding.  Advertising Strategy.  Marketing Research.  Messaging.  Market Segmentation.  Visual Elements.  Marketing via Technology.

A lot.

You can't be good at all of it.

So pick an area or two that has some real interest for you, or is a weak point at the place you work . . . and develop some skills around those areas.

If you have some time, you may want to get some general knowledge about the other areas, but if you can't . . . that's fine.

Always remember that you can outsource those marketing functions you don't do well, often for a relatively inexpensive amount.

So you can learn marketing research  . . . or hire a firm to do a project for you.

Learn the stuff that goes into an advertising strategy . . . or ask a volunteer to help you at.

Just remember that it isn't your responsibility to know "all things marketing."

Be strong in a few areas is good enough.