I've learned a few things by experience having now built my second home. What follows was written in answer to a forum question which was reworded then answered more succinctly. I put some real time and effort into thinking about what a first-time home builder might wish to know, so I thought I would share it here instead. This is far from comprehensive but contains some information I'd have found useful as a first and second time home builder.

First off, I have great news for anyone not already aware of this fact. You can get nearly everything you need for home building, legitimately, without spending very much money. The one item I was unable to create for myself is glass and that is because I do not yet have the glass smithing perk (I think). I'm actually not sure if that allows for making rods of glass or not to be honest with you, but I would think so. They must come from somewhere.

Here are the things you can do.

You can cut your own logs at the lumberyard. I have used the ones in Riverwood and outside Solitude and one other out in the boonies somewhere. You stand at the top of the ramp next to the pile of logs inside the roofed logging structure with the logs next to your left shoulder and the E option should appear if you're using a keyboard (not sure what it is on gamepad) which allows you to hook-hoist the log over to the cutting trough.

Then you hop across the log and walk forward a couple steps where you'll find a lever which will give you the E (or whatever) option again to begin the automated cutting sequence which automatically adds the log weighlessly to your inventory at "home" and also resets to start the process again once the log has been sawed. It's slightly slow and a bit tedious, but it's totally free and I have not found a limit on how many logs you can saw in this manner. It's how I built my second home. I suggest Riverwood because they're friendlier than that Orc outside Solitude or the guy with the 'tude in Dawnstar or wherever it was...yeeeeesh!

As for other materials, each home site has clay, stone and/or ore mining sites close by, so you just have to look around. I suggest you check out where the home sites are while you're here so you know where to do your search. They even supply the pick-axes for you.

It doesn't take long at all to get all the materials you need, except the iron ore, which you can buy tons of cheap from any blacksmith under the miscellaneous items if you're in a hurry. In Riverwood you can even work much of it off. Remember to check mines too, where each kind of ore is just lying around for the taking (depending upon the mine) and mining. Just about every one of them has iron ore available. The home site in the Pale, near Whiterun, has a Corundum ore mining site just steps away from where the chest and workbench are situated. 

The only material you have to out and out buy as far as I know (if you don't have the glass smithing perk), well, glass. That you can get from I believe it's called "Bits 'n Pieces" not far from the gates inside Solitude and from other general stores as well.

Hope that helps. : )

A couple thoughts you only need read if you're interested in home design and decoration:

The difference between an armory and trophy room may not be obvious to everyone. The trophy room limits the player as to what s/he can put in it (draugr, dead animals, skeletons, dragon head, spriggan, hagraven) while the armory is for armor and weapons display and is limited only by space and imagination. Bear in mind that each cellar has the capacity (is actually intended for) a complete armor/weapons building station which provides the smith with the means to move from ore to complete and polished product.  

In addition if you choose to build the storage area then add the armory on a connecting wing you can have a wrap-around outside deck which, depending upon the location, is a desirable bonus. (Definitely my plan for home three, which is going to be my personal space. No kids, no husband, no steward. Just my own private get-away.) Sigh... If this were real life I'd be set except for that little civil war thing...

Some other things I also wish I'd known before building...

Any home can have enchanting and alchemy stations. You don't need special towers or wings for that purpose.

If you don't plan on doing a lot of major cooking, the kitchen is a total waste of space. Skip it. You'll still have a huge lovely fireplace and place for your spouse to cook. The only 'plus' the kitchen has is an oven for baking fancy pastry and breads. You get a hard worker bonus accomplishment for cooking them but aside from that they serve no real purpose, at least not at the level of alchemy, smithing or enchanting.

Something else to consider:

You don't exactly "need" a bedroom wing, though be advised that if you have a steward, that person will be sharing your home, including your very open-concept three-bed (one double and two singles) sleeping area with you and your spouse and children (or worse, sleeping next to your lone young child, possibly of the opposite sex, in a bed three feet away if you only adopt one). I'm not sure I'd want some 40-some year old bald guy snoring away on the opposite side of the wall from me, much less within touching distance of my soon-to-be-budding daughter! Then again, in war-time at least she'd be secure with a spell-sword that close at her side while she slept.  (Now I feel like writing a story, which I'm sure many of you feel I'm already doing here).

If you only have three beds and two children (and are an immersive player) it's going to leave you wondering just where that steward is spending their nights once the children arrive.  

...especially if you're a married female player with a husband and a female steward,  which is, admittedly, highly unlikely given we tend to be brighter than that, but we don't always plan on marrying and stewards kind of come with the property if we just promote our housecarl. It happens. But in that case, I'd defintely say screw the greenhouse and opt for the bedroom wing or you may end up with more children than you planned, especially if you married Vorstag who already 'sounds'' 'like Arnold Schwarzenegger!

Moving right along... I've said this before, but if you're particular at all about how your place is decorated, do it yourself. DO NOT LET YOUR STEWARD DECORATE!

On the other hand, if you don't care about that stuff, let them fill your house with rotting animal carcasses, cluttered boxes and barrels, mops, buckets, dirty rags and mounted horker and skeever heads all over the place, and let's not forget the hanging racks of carrion everywhere. Very "rustic". It's very masculine to have a home that smells like a ...............c h a r n e l house.

The furnishings you can make yourself are more than enough to fill the home and the game still adds plenty of homey decorative touches to what you make for those of us, like me, who do not know how to use the console to place objects at will. (I tried once; it was a disaster). That's what brought me here in fact, yet here I am writing away...

***Final hint: If you don't make the two "small square tables" for the main downstairs hall, you will save yourself a TON of junk, boxes, burlap bags of nothing, mops, buckets and generalized useless clutter under both sets of stairs!*** 

I was THRILLED to see that particular eye-sore from my first home so neatly and easily done away with by not doing something when building my second home. I even did a save and built one of the tables just to see, and sure enough it came with an immediate load of various sundry and assorted effluvia, which anyone who owns at least one Hearthfire home knows only grows over the first several days the home is in place.

I'll add pics from both houses so you can compare the steward's/game's decorating style vs my own when I'm more alert, awake and oriented. Until then, happy adventuring!