How do I enter the traffic pattern if I am coming from a nonstandard direction?
I am answering this question based on U.S. operations and a plan to land on runway 36 using left traffic:

My opinion - 

Option 1: If you are arriving from east of the airport (from 090 or 020) you should fly over the airport at an altitude well above pattern altitude, observing the traffic (if any) then descend to pattern altitude west of the airport well beyond/outside the traffic pattern.  After that enter left downwind at midfield from a 45 degree angle at pattern altitude.

Option 2:  If you are arriving from east of the airport (from 090 or 020) and have determined (visually and monitoring the CTAF) that traffic is extremely light or non-existent, flying over the airport and entering directly to a left downwind at pattern altitude (not descending) is an option.

Entering the traffic pattern after approaching the airport from the south or west (from 180 or 200) should be done by maneuvering west of the airport, well beyond/outside the traffic pattern, until you are able to enter left downwind at midfield from a 45 degree angle at pattern altitude.

See the examples from the illustrations below and familiarize yourself with AC 90-66B, which is an excellent guide.(illustrations below are from AC 90-66B)