I have my tongue and groove pine material that I will be installing on our covered porch in a couple of weeks but wanted to stain the boards first before installing them. I plan on using a Behr semi transparent stain in semi gloss finish. Does anyone have and tips on things I should do for a good quality result? Do I need to sand the boards ahead of time? Is one coat sufficient? Also I was planning on using oil based stain. Thanks.

You should stain it before it goes up for sure. I used a Thompson Waterseal product on ours. It is a stain and sealer in one with a mold inhibitor. It still looks good after 5 years.

I did the same last year, used oil based and I'm
happy with it. Definitely stain in advance, possibly 2 coats, I brushed.

I would not sand in advance, for a ceiling, I don't think you would gain anything from that effort.

Oil based and before you put up for sure. I like TWP oil based stain and they will ship it to you for free last time I ordered a 5 gallon container.

I started staining the boards last night and it went pretty well and quickly so far. I finished 12 of the 40 boards I have to do. I set up two saw horses in the garage and then moved the finished boards on top of some 2x4s on the floor to dry. I ended up brushing on the stain and then while it was still wet went over it with a foam roller to smooth out any brush strokes.