Whew.... you took on a big project in that conventional wisdom and your initial perception will be to get it done quickly. However, if you want something to look incredibly nice and professional (not like it was DIY), then plan on many steps and lots of time. First.... is the sanding and preparation steps. Probably the most over looked of any DIY finishing project. Once you have all of your wood acclimated to you room (at least 24 hours of "rest" in the room to get acclimated to temperature and humidity), wipe everything down with a rag soaked in mineral spitits. This will help remove any dirt, oil, grease or whatever may be present on your wood..... let it flash off and dry.
Then start your sanding process. I would highly recommend a palm sander or just a plain old sanding block. With the pine, I would probably start with #100 garnet sanding paper. Once everything is sanded, vacuum and then wipe your wood down with a rag soaked in mineral spirits. Let it dry, then move to #120 paper and repeat vacuum and cleaning. Go next to #150, then #180 and finally #220 repeating the vacuuming and cleaning between each sanding step. Do not skip steps in your sanding. If you skip and go to #180 paper after sanding with #100.... you will not smooth out the scratches or abrasions you put in the wood from the #100 paper. Take your time and do each of these steps fully and completely. You will have a much smoother surface and wood that will take your stain a lot better.
Now, once you're done.... you have a nice smooth surface in preparation of finishing. Pine however, is very un-eaven in how porous it is and generally stains up with a very splotchy appearance. So, a pre-conditioner is necessary. You can buy pre-stain conditioners redy-mixed off the shelf. However, I have found them to be very un-impressive in their performance. I like to use a shellac based conditioner for Pine, Poplar, Birch and other soft woods. What I do is use the Zinsser shellac based sanding sealer http://www.zinsser.com/product_detail.asp?ProductID=72
and cut it 50/50 with denatured alcohol. I generally give my raw (soft) wood two coats of this "conditioner" lightly scuffed with a 3M sanding pad between coats (always create test samples on scrap wood to BEFORE tackeling your entire project to be certain of your results). Wipe the wood after scuffing with a cloth dampened with mineral spirits and let your wood completely dry before the next coat.
Once you've conditioned your soft wood with a couple of coats of this home made conditioner.... you are ready for stain. If using an oil based penetrating stain, I like using the Sher-Wood BAC wiping stains from Sherwin Williams: http://www.sherwin-williams.com/pro/...ains/index.jsp
or an equally fine product from General Finishes: http://www.generalfinishes.com/finis...es/oilbase.htm
Using big box brand stains like Minwax, Cabot, Deft are ok.... but they just aren't the quality of the brands I've already mentioned or other professional grade stains like ML Campbell and Mohawk. A pro grade stain may be a bit more expensive on the front end, but you generally can stain in a single coat and have a MUCH "cleaner" final appearance prior to final finishing. Assuming you are using a pro-grade stain.... flood the surface of your prepared wood and let the stain flash off (dry to the touch). Then wipe it using a cloth soaked with mineral spirits and remove all of the excess stain. I can't stress enough the importance of having a LOT of clean cotton rags available. Once you start wiping your stain off.... your wiping rag will fill with excess stain and you will need another one. Let everythig dry for at least 24 hours after staining before final finishing.
For final finishing.... if doing a lot of wood like you are probably going to be doing.... a lacquer, alcohol or water based final finish would be the way to go because anything oil based will take several hours to dry between coats. Longer even if using an oil based polyurethane (which for me is NOT a good thing because of all of the "dust" and particles that get stuck in the finish). What I would do if it were me.... and remember, I tend to be a bit anal in my finishing schedule (but my stuff usually looks darned nice if I do say so myself), is give my newly stained wood a couple coats of sanding sealer. I would use that very same DE-WAXED
shellac based sanding sealer from Zinsser that you used in your wash coat. Two coats of the de-waxed shellac will help seal your wood and start a nice build toward your final finish. You can very lightly
scuff between coats with a 3M synthetic pad. Wipe the sanding dust off with a cotton cloth dampened with mineral spirits and then a final wipe with a cloth dampened with water.
I would then finish the wood using a water based final finish of your choice. I am using the General Finishes Polyacrylic: http://www.generalfinishes.com/msds-...lic-062805.pdf
on a project right now. Similar to yours in that mine is a bunch of molding which I am staining and finishing for my family room. I ran a test between the General Finishes Polyacrylic and that from Minwax.... and it wasn't even close. I had to constantly stir the MW product and it was a lot more "sticky" than that from General Finishes. The General Finishes product flows out like brushing finish on glass. No brush marks and it's crystal clear. I'm putting three coats over two coats of the de-waxed shellac sanding sealer.... scuffing between each coat with a synthetic 3M pad. A lot of steps for sure.... but my finished product has a lustre and appearance that you just find yourself wanting to "touch" and rub your hands along. LOL.... kind of like that "wet paint" sign when you see it. You just HAVE
to touch it to make sure.
Now, if you own or have access to spray equipment and are adept at using it.... you can accomplish the "finish" process even faster spraying a vinyl sanding sealer and then a few coats of coats of lacquer. Lacquers dry in mere minutes and you can build several coats of finish in just a couple of hours. However, with most lacquers you have fumes and odors that aren't good for anyone (especially the baby) But, alas, I don't have the space for spraying, nor the professional equipment. So, I have to do everything by hand. Nor, do I have the worry about fumes.
Good luck with your project. Take your time.... don't rush things or skimp and practice, practice, practice on scrap getting everything right prior to starting your entire project. Make a finish schedule on your scrap so when you find something that you like.... it is repeatable.