I just did something similar. I'm going from no sailboat to two sailboats in one week. I'm getting the paperwork for O'Day 23 pop top this Saturday (price $0, condition terrible) and just bought an O'Day 22 yesterday (price $350, condition terrible). Now if only I knew how to fix them! Going to be asking a lot of questions here....
Okay.... great! You are on your way ... So I've done this 6 times now. And I've made some mistakes and spent money I didn't need to... so.. Here is some of what I've learned.... you never save time by taking a short cut. You end up going back and undoing something and redoing ... and being unhappy with the results so...
First, take lots of pictures of how things are laid out.. then you will want to remove as much of the interior as possible. Take out any rotten bulkheads, bunks, galleys etc. Keep them for templates. Put any usable hardware (like stainless screws, galley sink etc) in zip lock bags and label them with a sharpie so you know what they go with. Then go inside with a pressure washer in one hand and a shop vac in the other and get her clean.
Next remove
all of the deck hardware (rails, cleats, winches etc.). I even go so far as to remove the ports...Make sure you take pictures first and have those zip lock bags handy to put stuff in. Pressure wash the top side and hull. Sand lightly with an orbital sander, patch any unwanted holes with a small piece of fiberglass cloth soaked in resin (see note below), fill with bondo, pressure wash again and then paint. You can buy expensive paint but I've found that Rustoleum works great (it is a high quality enamel). And with Rustoleum you can always find a color match later when you want to touch up a ding or a later modification. Replace the deck hardware. You will want to make new backing plates. I've found that one piece of the faux wood decking (HDPE) is enough to make all of the backing plates you will need, it will never rot nor host mold spores etc. Good stuff. You will also need to rebed all of the deck hardware. I've used the 3M stuff. It is messy and you always seem to get a little on your new paint job. Many people here on this list swear by butyl tape and I'm going to try that for my next project boat. It looks like a simple and quick way to make sure you have no leaks into the boat.
Now you are ready to pain the interior. Don't go on the cheap here. Get a high quality exterior grade latex and ask the guy mixing the paint to add the anti-mold additives. This will keep your boat smelling nice for many years. Home depot lets you add the additive, Lowes has a base with the additive already added and you select the pigment. Next cut out new bulk heads, paint or stain and replace those....
If you can reuse your cushions be sure to kill off any mold spores first. Get a kiddy pool, fill it with bleach water and soak them for a bit. Put your anchor on the cushion so it wont float in the pool.
Now for the electrical...Go to Lowes or Home Depot and get some of the low voltage wire used for landscape lights. This stuff is made for 12V and it is also made to be buried underground in wet conditions... so it holds up well... and it is way cheaper than marine grade wire. Get some crimp connectors and heat shrink wrap. Go to Auto Zone and get some 12V switches and now you are ready to replace all of the lights. I have tried reusing thelight housings from my old boats with poor results. Go to WalMart and get you a new LED bow light, and stern light. For cabin lights go to Tractor Supply and get you an LED white trailer light or cabin light. You can use these for steaming lights also.
For the electric connector that goes from your mast and into the boat. You can buy these but they are not cheap. I use a simple trailer harness connector ($3 at Auto Zone) and just drape it through the hatch. One less hole in my deck.
A cheap and easy way to recover your cushions is to use fleece. You can buy it in big rolls at a fabric store and often with colorful nautical themes. Lay the foam on the fleece and cut the fleece leaving about 4" of fleece hanging past each edge. Then use a scissors to cut the edges of the fleece into strips that end about 1/2" from the edge of the foam. With the foam sandwiched between the two pieces of fleece, tie the two pieces of fleece together using the strips you cut. It leaves a nice frilly edge and it is fast, cheap and efficient.
This sounds like a lot of work but if you do it systematically you can get her done in about 15 days of work (seven weekends or one week and three weekends). When you are done you will have a boat that people will complement at the launch site, smells nice inside, is clean and... you know all of your deck hardware is sound, etc. And it will be done right and won't require a lot of work each season to keep it going. And I've taken a $500 boat and after doing this kind of work sold it for $5K. It really does make a nice finished product if you do it right.
(Note on fiberglass patches! When making fiberglass patches, cut out the cloth to the size you need, lay it out on a piece of visqueen -- the plastic sheeting used to catch paint drips-- and then wet it with resin while on the visqueen. You can then add a second or third layer of cloth right on the visqueen. Make each piece of fiberglass cloth slightly larger than the previous piece. Wet them all thouroughly and make sure there are no air bubbles. Squeege any excess resin and now you can then take the visqueen to the hole to be patched and smash the fiberglass cloth over the hole. Hold it in place with the visqueen for a few minutes to let the resin bind with the hull. The visqueen does not stick to polyester resin so you can then remove it and fair out the edges of your fiberglass patch. This method is a lot cleaner and you are less likely to get the resin all over the place -- and on you)
(Note on painting! The roll and tip method will give you a very nice finish. If you want anti-skid topsides you can use the garage floor epoxy sealant sold at Lowes -- also a Rustoleum product -- and add the grit.)