Hi there Dales W
Apart from the Gerlan Yr Elen traverse of Lewellyn, by far the best approach and easiest route up Lewellyn is from that small car park in Cwm Eigiau.
Even as early as 7 am the car park fills up quickly.
There are two styles in the carpark, the one you need to take is the first one on your right.
You follow the clear path all the way until you eventually go around the corner at the top.
In about half a mile you will come to another style with a gate.
Once you reach this final gate, you should see some rocks up to your left.
There is a very clear easy path that follows the adjoining brickwall.
Weather permitting you should clearly see a well worn path that follows the hillside.
This path is quite eroded in places,and if followed will bring you out on the main Central Carneddau ridge at a height of 3189ft or so.
To your right will be the clear path to Foel Grach and to your left the route to Lewellyn.
My description sounds rather complicated i know, but in perfect visibility the route is never in doubt.
Apart from the overall length of this walk, there and back around 8.5miles, its one of the most rewarding and easiest ways up Lewellyn.
I know i will be criticised for saying it again,
This is a walk only to be attempted in good clear weather, i cannot imagine the technical difficulties in trying to navigate this part of Snowdonia in heavy mist.
A huge expanse of very high mountain terrain mostly above 2500- 3000 ft in height, with not a single feature to navigate by.
Many walkers new to the Carneddau try to navigate in such weather and regret the decision.
I tried it once with friends some years ago,and did not get as far as the last style, visibility was zero, gaining the path impossible.
Choose a nice day,and you will be rewarded with one of the easiest and most enjoyable walks anywhere in Snowdonia, with not a single piece of litter in sight,and only the occasional walker to say hello to.
Now thats what i call paradise.