Constitution is a particularly beautiful subject for modeling, although quite a challenge to do well and not generally recommended as a first effort. I presume you have far more knowledge of nautical nomenclature and marlinespike seamanship than most novice modelers and that should serve you well. That said, I would strongly urge you to complete the Model Shipways three kit "novice series" mentioned previously. It is designed to progressively present basic modeling evolutions which will prepare one for more complex models later on. As you've probably heard, there are a lot more complex (and costly) ship model kits purchased than there are ones that are ever finished. Complex builds tend to become increasingly challenging as construction progresses.
I don't know which Constitution kit you've purchased. They all seem to have their particular "kinks" and it's best to carefully review as many build logs as you can, particularly those for your brand of kit. This will prepare you for any inherent difficulties with your kit and their solutions.
I know that with everybody blowing encouraging smoke up your kiester, this is going to sound like the guy who said, "Other than this, Mrs. Lincoln, how did you like the play?" but I expect a few general suggestions for success that aren't in many instruction manuals I've seen over the years will be of perhaps presently unanticipated value to you later on:
1. Take your time. Never rush. Treat each part of the model like a model in itself. Strive for sharp edges, perfect fits, and perfectly smooth surfaces.
2. Take care to ensure that your "backbone," setup is absolutely perfect. Fair your bulkhead edges accurately and test them for fairness in every direction with a batten. (Carpenter's chalk rubbed on the batten will transfer to the high spots, identifying them. A batten with sandpaper glued to it can be used to fair the edges of bulkheads.) This step cannot be emphasized enough. If your setup isn't perfect, it will cause you nightmares when you try to plank it. Follow proper planking protocol: shape your planks perfectly before you hang them. Do not try to forcibly bend planks on the hull structure.
3. If anything isn't perfect, disassemble it and do it over again until it is correct. (For this reason, most experienced modelers use "reversible" adhesives which can be "undone," rather than permanent adhesives which might require destructive removal in order to correct an error.) The ultimate quality of your finished work is dependent upon the perfection of all the parts. Some will tell you "Perfect is the enemy of good enough." That may be true in a lot of things, but not in serious ship modeling.
4. Anytime you are using a new adhesive or paint, stain, or varnish, test it first on a scrap piece to be certain it is compatible with the substrate and any previously applied base coats. Be aware that many adhesives will soak into bare wood and affect the appearance of later stains and varnishes, and many coatings are incompatible with previously applied ones. All wooden parts should be sealed before applying base and finish coats. (Shellac is a good sealer for this purpose.) Do not attempt to fill surface flaws with thick paint or varnish coats. Make sure your parts are smooth and dust-free before applying finish coats. Apply paint as thinly as possible. Thick paint coats destroy scale detail. IMHO, more otherwise well-done models have been spoiled by poor paint jobs than anything else.
5. Always remain aware of the scale and what is and is not visible at "scale viewing distance." (E.g., a 1:48 scale model viewed from two feet away should look like what the viewer would see if they were viewing the prototype from 96 feet away.) Resist the urge to add out-of-scale detail. The most common of such errors are things like wildly oversized fastenings of contrasting color on planking and copper hull sheathing tacks which are invisible at scale viewing distance.
6. As Constitution exists and is extremely well documented, the modeler has little or no latitude for "creativity" and any deviation from her actual appearance (presently or at some depicted specific point in her long life) would be a glaring error. This isn't to say that every modeler isn't entitled to do whatever they want with their model, but where one is building a particular named vessel, the accepted convention is that the model should portray the prototype as accurately as possible.
Finally, I would strongly advise you not to use expanding foam on your model without conducting some fairly extensive experiments. Planked model hulls are surprisingly strong structures when completed but remain somewhat unstable until all the elements are connected. Expanding foam is capable of generating surprisingly powerful forces as it expands. Such expansion may push your bulkheads out of perfect perpendicular alignment with the keel, for example. Such misalignment can cause major difficulties as your build progresses and could even ultimately change the shape of the planked hull itself.
And, of course, don't forget to enjoy your modeling!
