Doing a lock on your own is the same process as doing it with crew but you need to do everything yourself so the steps are modified thus:
1. When you come up to the lock landing, you’ll need to tie the boat up while you go and set the lock. Generally this needs no more than a simple knot of the centreline over one of the bollards. You certainly don’t need to tie front and stern as if you were mooring for the night, it’s got to just be enough to keep the boat from floating off while you set the lock (being aware that as you empty or fill the lock, there will be a certain amount of push or pull on the boat from the water flow, so your knot needs to be reasonably sturdy)
2. After setting the lock, you then need to return to the boat, untie it and bring it into the lock.
3. Then you need to get off the boat and up to the top of the lock. If the lock is full because you’re going down then of course you just step off. If the lock is empty because you’re going up then there are ladders set into the lock walls for you to climb, or in many shallower locks you can simply clamber up straight onto the side.
Be very careful as you go because, being solo, if you slip there may be no-one to help or even hear you shouting. Take the boat’s centreline as you climb out, you’ll need this to control the boat as there’ll be no-one aboard. Don’t forget your windlass either.
An alternative that is often used by confident solo boaters, especially coming into wide locks, is to steer the boat close to the side as you bring it in, drop the engine into neutral just before it gets there, and step off the boat carrying the centreline, walking alongside the boat as it then drifts into the lock. If coming into the lock from below, you’ll need to walk up the steps set into the lockside. Don’t drop the rope!
4. When you empty a lock of water with a boat in it, the boat will gently drift forwards towards the lock gates. This is not usually a problem but do keep an eye on the front fender to make sure it doesn’t catch on the gate. Equally, use the centreline (loosely tied around a bollard) to ensure the boat doesn’t drift back to the point where it might catch on the cill. However, be very careful with tying the line because as the boat descends, it can easily end up hanging by that rope – which can then snap – dropping the entire boat crashing down to wherever the water level got to. When I did locks solo, I only used the tied centreline while I was initially opening the sluices, then loosened it while keeping watch to ensure the boat was staying safe.
When going up, use that centreline tied firmly to a bollard to stop the boat slamming backwards as you start to let the water in. As the boat rises, the rope will become more slack but by then the effect of the water ingress to the lock will be less so the rope can generally be untied anyway.
Be very wary of distractions. It is absurdly easy to enter into conversation with passers-by and other boaters and forget to keep an eye on the boat. This is how accidents and sinking happens…
 Holding both rope and windlass as you climb a lock ladder is sometimes dangerous. It can be safest to fling the rope up onto the side of the lock, and carry the windlass in your belt or a special windlass holder clipped to your belt, so that both of your hands are free to hold the ladder.