I'd second the motion on a Japanese hand saw (given that you don't want to purchase a circular saw).
However - if your only power tools choice is a jigsaw, you can make very straight cuts by using a straightedge (or an edge guide) as a fence. Trying to cut a perfectly straight line free hand with a jigsaw is an exercise in futility.
As far as dust goes - if you're cutting with handtools, I wouldn't worry about it - if your using power tools, a cheap throw away particle mask is more than sufficient.
A forum community dedicated to professional woodworkers and enthusiasts. Come join the discussion about shop safety, wood, carpentry, lumber, finishing, tools, machinery, woodworking related topics, styles, scales, reviews, accessories, classifieds, and more!