If you're looking for a sewing machine, the best piece of advice for you can be expressed in three words: all-metal frame. Be willing to pay for it, and resist the temptation to blow a few starter bucks on a cheap piece of equipment. Plastic parts, I am told, will get you only so far before the entire machine has to go.
One fancy-schmancy feature you will want is an automatic buttonhole setting. This has sped up many a process of creating coats and weskits. Granted, my buttonhole stitches aren't exactly top-notch, but it's better than doing it manually. Ironically, I have had to work the automatic buttonhole process semi-automatically when I needed buttonholes longer than the special buttonhole foot would allow. In those cases, I just manually flicked the mechanisms the foot would automatically trigger in its stitch path and got what I needed.
Best of all, this first machine for your humble servant wasn't ridiculously expensive. I paid $140 at Walmart. Not a bad deal at all for a workhorse.