Keep yourself covered – long pants, gaiters and socks help keep the bugs (red ants) at bay and gloves will protect you from stinging nettles and thorny branches.
Get reasonably fit – the trek is usually a physically challenging and tiring mission through rough terrain, so you want to be relatively fit.
Be equipped – carry enough water, waterproof bags for your camera and insect repellent as well sunscreen and a hat.
Stay warm and dry – take warm and rainproof clothing with you to cope with the cold conditions up in the mountains.
Join an organised trip – book through a tour company to simplify your travels and get the gorilla permits arranged for you beforehand.
Choose your timing – try to avoid trekking in the rainy season (March to April and October to November) when the going gets tougher.