Macs,
Skills yes! But remember we knew nothing different as we simply had no Nav aids. Not even a Radio Compass. Met briefing was important but sometimes there was no met information on the destination available and worse no let down facility there...Take the case of Mogadiscio for instance...All they had there was a radio, but all that radio could do was talk and listen to you from fairly short range. They could not give you a bearing or course to steer or anything like that. You had to FIND the place visually and usually with not an enormous amount of fuel to spare.
I remember two Eight Squadron chaps at Khormaksar who needed to take a Meteor T7 down there for some reason. They spent two days planning that flight but had no real met information when they took off. More than halfway down the ground became obscured by an overcast of stratus...They proceeded on DR till certain they had passed the coast and let down to emerge correct to estimate over the sea. They turned back and soon sighted the coast...They even got radio contact with Mogadiscio which is vertually on the coast...But, which way to turn, left or right? How long to proceed along the coast before turning round and looking the other way?
The Meteor 7 just has one ventral tank for extra fuel and even with that, there is precious little range...The couldn't find it and ran out of fuel. They baled out (no bang seats) and one survived, the other got fouled on the canopy strut and went in with the aeroplane.
So the short answer to your question is that there is an element of risk. The more normal destination would have some form of let down...Even at Nairobi Airport (Embakasi Civil Airport) where we based our Hunters, we taught one of the civil controllers, Ron Garside, how to give us a Controlled Descent (QGH). It did of course, have an ILS but that was completely useless for our Hunters as we had no receiver or instrument for it. So basically for jet fighters in those days, the only way to get down at your destination was a QGH from the ATC Controller. The limit for such a letdown was basically 500 feet AGL, so with a cloud base lower than that you would be diverting (preferably before commencing your descent from altitude). If it was a big fighter base like Wunstorf then they would also have a GCA (Ground Controlled Approach) and that could take over from the QGH and then the GCA controller would give you a full radar talkdown right down to about 200 feet or even lower unofficially.
As for fuel planning...Well fighters are a bit different from airliners etc. in that you just "Fill it up". If it is a long flight then you fit the necessary number of droptanks. Then if the published range adjusted for the day's winds does not provide enough to go there and at least divert to your alternate with a bit of spare, then you don't till perhaps tomorrow!
Thunderstorms...Well normally the tower could tell you how fast it was moving and when it was likely to clear and you could make a decision on that.
The worst thing is Sea Fog at some coastal airfields...This could roll in very fast and catch you out.
Getting LOST is unusual but I was in a formation once that did get completely lost and that stretched to Mayday! Mayday! Mayday!...But that is another story Macs
BTW when I joined BEA, Heathrow still had an operational GCA approach and I remember doing one as a Second Officer and in very severe turbulence while I was still being trained on line...I was very pleased when the Training Captain, Sandy Sanderson, said to me at de-briefing "That was a pretty fair fist of an approach!"