Practice on some cheap softwood.
start by trying a dry run -the key is learning where to hold the router, how to move you feet forward, how to position the cable and how to deal with entry and exit points.
If they are stopped grooves, I would do plunges first at beginning and end, first form a hole, then move cutter a few mms and plunge again, do it until you get a bit of a slot.
If they are through grooves, then maybe clamp a long bit of timber that overhangs the ends and run your router against that.
If you are doing a groove that is wider than the cutter, when you adjust your fence for the 2nd pass, make sure you are running the router in the correct direction…..it may not be the as the first pass.
Also and especially in oak don’t take too much off.
Make sure your plunge action is nice and smooth, wax the rise and fall chrome bars if necessary
Check the bottom of your router, I always sand a little round on the edge of the bottom plate to make sure there’s no rough bits that might snag
