Go beneath the underpass at Tarbet railway station and walk into the forest. After about 100m veer right at junction. After approx another 150m, at another junction, take the obvious uphill path.
There are signs saying felling operations are underway and not to proceed. If you do proceed, you will find obstacles in the shape of trunks felled across the path. There are handwritten signs taped to trees to guide you through the woods.
On the open mountain a singular path leads all the way to the summit. The path is boggy in places and there are holes to avoid. Up top the views are stunning in all directions. You could pass an hour up here admiring the surrounds.
I returned by train to Glasgow, and the views from the West Highland line as it wends its way slowly from Tarbet to Garelochhead are equally fantastic. That the trailhead begins at Tarbet station makes this an ideal rail-walk combo - and a five minute stroll from the station leads to Loch Lomond's shores. What more could a poor boy ask for? Linkback: https://mountainviews.ie/summit/B91/comment/23668/