Here are some suggestions to follow when renovating your staircase.
Ensure you can manage without access to your home's upper floors for several days
If possible, you should try to arrange your home so that you can manage without accessing its upper floors for several days. If you only want the contractor to make a couple of small changes to the staircase, they might be able to get the job done in under a day. Anything more elaborate (such as replacing the staircase's spindles, or refinishing or replacing all of its steps) will take longer than this.
If you insist that the contractor squeeze all of these tasks into a single day, because you don't want to do without the staircase for longer than this, then they will have to work in a speedy manner that won't give them as much time to evaluate and, where necessary, improve their work. Even if they are excellent at renovating, their work might end up not being quite as perfect as it normally is if you force them to do it too quickly.
By setting up, for example, your sofa bed so that you can sleep on it comfortably for a few nights, instead of using your bedroom, and by putting all of your toiletries and bath towels in your downstairs toilet (or arranging to use a local relative's bathroom), you can give the contractor all of the time that they require to provide you with a beautifully-renovated staircase.
Decide what to do with the area underneath the staircase
If there is a cupboard or an empty space underneath the staircase that is not yet decorated, you should consider getting the contractor to renovate this along with the staircase. The reason for this is as follows; if for example, they refinish your steps, fit a lovely new handrail and repair the damaged spindles, but the area below this renovated structure is a mess (for example, if the varnish on the cupboard's door is peeling off or if the empty space is unpainted), then this area will ruin the beauty that the finished staircase creates in your hallway. Getting it done at the same time (and ensuring that it is decorated in such a way that it complements the new aspects of the staircase) will ensure that this area has a finished look to it and that there is nothing in it that spoils the beauty of the renovated features.