Ah! Nearly missed this Post...
I know I'm the only Fokker E4-Fan since Immelmann, so here are some Recommendations:
At first I'll have to mention, that the E4 is a real Pretator, once you've spent some Time in it. You can easily outmatch multiple N16s. Only the N17 can be of some Danger, but that doesn't mean that you'll have to run away from it. Just pay a bit more Attention to what your Opponent does (N17s are usually flown only by Aces @ that Time)
The first Advice sounds silly, but ends up in a different Flying-Tactic, so:
-Don't get hit.
One single Hit can be enough to damage the Steering-Wires, which instantly ends in a pretty scary Emergency- / Crashlanding.
To avoid Hits, you need to stay out of the Firing-Angle (FA) of your Opponent at all Costs. When he is close to reach FA while circling - break up Circle by eihter a steep Drop or a near-stall Climb.
It doesn't matter if the Opponent gains Height or other Advantages through that. He is outside FA, that is all that counts.
Same for Circles, that end up in both Planes facing their Noses at each other. No Chicken-Runs. No Jousting.
-The E4 is powerful but tardy, use that to your Advantage.
You can eihter climb or fly a tight Curve - not both at the same Time. First, let it drop a bit to gain Speed, then pull up again and turn sharply. Repeat that. This Way you can fly tight Curves. That is some Kind of "Power-Drifting" (works fine with Albatri, also).
The E4 climbs well, but more important is the Fact that it gets slow really quick by that. Almost like hitting the Brakes of a Car. It can reach an impressive Climbing-Angle, but it is extremely unstable, there, and needs constant Control-Input to keep the Nose upwards.
-Lure them into Diving at you.
When they are behind you and diving into you, drop for Speed and perform a tight "Power-Drift" as described above. If he is good, you both now are at same Level in a Circle @ same Speed, if he is not so brilliant, you can look for him waaaay below you...
-Don't follow Climbing-Circles.
As soon as the Nupe realizes, that the Idea of attacking you was not so good, they often go into a Climbing-Circle to get rid of you. The E4 cannot follow, there, so just climb straight and try to climb higher for as long as he stays in Circle. He will eventually stop and run Home @ Full Speed, so you might want to climb West or South, depending on where you think he wants to go.
Okay, you are not the fastest Plane in the Air. The fleeing Enemy is too far away for a clean Shot. Shoot anyway. You just want him to stop flying in a straight Line Home and evade your Bullets instead, mostly by a Circle. That gives you the Opportunity to catch up. You will need a substantial Amount of Bullets for that, but you have more than enough aboard.
-Problems mean: Go Home.
If you fire at someone and hear your own Plane making scary Noises, the Sync-Gear is broken and you are damaging your own Plane by Firing. Stop and go Home. The Double-Row-Rotary is legendary... for it's bad Reliability. If you feel, hear or whatever anything, that is not Normal, turn around and go Home... and keep your Finger on the Ignition-Kill-Switch. It is not unusual, that the Engine explodes into a big Ball of Fire. If you turn off Ignition fast enough, the Fire stops.
The E4 needs considerably more Speed just to stay in the Air than other Planes. I like Wheels to touch the Ground a bit before the Airfield even starts - I gain some extra Meters to roll.
Hope that has helped a bit to convert more of you into E4-Fans