You might want to ask the marina or storage
yard if they allow it first, but assuming they do then please replace the main and the spinnaker
halyards if they are a bit ropey. You need one for hauling and one for safety
just in case.
Whilst a bosuns chair is okay you will have difficulty working on the top of the mast
because they don't go high enough. However, there are other alternatives. I use a flexible mast climbing ladder, others prefer a harness with prussic knots etc. Worth doing a search on here.
The other option of course is to take the mast down, which means you can work on it properly at ground level. Then you can really check it out, see the lights work and the VHF
etc are in good condition.