I am by no means an experienced hiker, but I do exercise regularly. This is a challenging climb, no matter what route you take and which peak you decide to end up at. I believe most people end up at Bukit Tabur East peak, as I did.
From a tourists perspective, my advice would be to do the hike with a local, either through a paid tour, hiking club, etc. There are ropes to assist with the rock climbing sections (and you will need to rely on them), so wear appropriate gloves and footwear.
Keep in mind there are no safety rails or any other safety mechanisms