For something that is intended for use and abuse, you can't beat a worm
drive saw. In my years on construction, the Skil was the choice of 98%
of the carpenters I knew. To make straight cuts, use striaght edges,
and squares. They don't make as accurace cuts as chop saws, and table
saws, but if you have a good blade, and jigs, it comes close. Thin kerf
blades are nice, but for free hand cuts, you have to be very steady,
because the blades can flex while cutting.