Great advice above -- jump in! Back when I first started messing around with fretted instruments all of my answers came from the books I was able to find. Things have become much, much easier. Google, for example, "fret cutting jig" and you'll find all sorts of things from commercially available jigs to things folks have cobbled together in their shops. Remember, when searching for information, that a ukulele is in many ways a downsized guitar, so much of what you find from builder's guitar shops will apply.
Take it step by step and don't become obsessive about either perfection or finishing within a fixed length of time. For example, prepping, slotting and fretting the fingerboard can be considered it's own project. There are lots of Youtube videos that are very good and go into plenty of detail.
You can -- and should learn how to -- make your own templates either from the plans of others or your own if you're going to keep at this.
Fretting, scale length (positioning the bridge/saddle) and that sort of thing are matters of measuring accurately and double checking before gooping things together. Good measuring tools are invaluable.
Spending all the time others have suggested reading and watching videos, take into account what type of neck to body joint looks good to you -- and the least intimidating. It's one of the trickier bits, particularly where glue is involved.
Handle as many ukes as you can, be it in retail stores, uke groups or whatever. Play and learn to listen carefully. After awhile you'll be able to assess a lot about a uke just by picking it up and feeling both its weight and balance. Read a few articles on stringed instrument acoustics so you have an idea about things like wood choices, top and bottom thickness, bracing patterns, etc.
Keep it fun! This isn't a college course and there are no tests. Just sort of absorb information as you can. You don't have to memorize anything because it's all within reach if you've got a smartphone.
Oh yeah -- while you're doing all of that I heartily agree about the kit idea.