Simple Table Saw
To me, much of the fun of woodworking is making my own tools and jigs and then using them in a project. Jigs made of wood do not last very long, since they either wear out, or warp (or both!), so making new jigs is a constant process. The trick is to keep it simple, so that any worn or damaged guide piece can be replaced quickly with whatever is in your scrap wood bin.
Table Saw With Guide
When machining large pieces of wood, it is best to keep the wood still and move the machine, so a hand circular saw is a must have. However, when working small pieces of wood, it is best to keep the machine still and move the wood, so a table saw is also a must have. A table saw can however be rather expensive and a cheap, inaccurate, wobbly one, costs 3 times more than a hand tool.
Making your own table saw with an upside down hand saw is not difficult and it also has some advantages, notably that cutting through the table results in a zero clearance blade slot, which helps to reduce tear-out. I set the blade to 90 degrees and leaves it that way. I never cut at an angle with a circular saw, since it much increases the danger of a jam and kickback, which can hurt very badly. I rather use a jigsaw for fancy cuts.
When selecting a circular saw, compare the different models on display and select the one with the sturdiest guide plate chassis. The biggest problem with DIY tools is wobble. Makita saws are very sturdy, while my other cheap American saw is rather wobbly, so I learned from the experience.
I made an Ikea scrap wood MDF box with a top and no bottom, to house the saw. To adjust the blade height, I tip the box up to get to the lever and since there is no bottom, saw dust falls out and doesn't build up in the box. However, it is a good idea to cut a hole in the side for a vacuum cleaner nozzle, to reduce the dust flying up into the air.
When using the table saw, I clamp a piece of wood to the back of my work table, to keep the saw box from sliding off. That works well enough.
Simple Saw Guides
The top overhangs the sides of the box by 5 cm, to enable the use of simple guide blocks and clamps.
The saw guide (Yankees call it a fence) slides along the front side, wraps around the table edge and clamps in place. The guide ends at the middle of the blade. At that point, the wood is cut, a longer guide doesn't help anymore and could cause the wood to jam between the guide and the blade and get flung back at high speed, which will hurt badly, so I keep the guide short. American table saws have guides that go all the way to the back of the table - that is not a good idea.
When you make the guide, glue the pieces, then clamp them to the blade and the front edge of the table. By doing that, the guide is guaranteed to be perfectly parallel to the blade, even if the table edge is not. Once the glue set, you can add a couple of screws if needed.
Yootoob is full of fancy saw guide designs. If you make a fancy guide, then when it breaks and/or warps, you need to spend a lot of time making a new one. So I keep it simple, don't make fancy sliding slots in the table top and use a G clamp to secure my saw guides to the table edges. A saw guide could be as simple as a piece of junk wood that was lying around, or a plastic rafter square.
To use a saw guide, clamp it lightly with a G clamp to the table edge and adjust it with a rubber mallet, then tighten the clamp.
I cut with the blade set much higher than the wood thickness. This directs the cutting force mostly into the table and not at me, which reduces splintering and also reduces dangerous fly-back of wood pieces. It is a good idea to use a smaller size saw (a 5 to 7 inch blade is enough) with less power. You will never be sorry if your puny little 5 inch table saw jams and stalls - while you will be very sorry for yourself if your saw goes Whump! and throws the wood piece back to you at 100 miles an hour.
A ten inch table saw is a killer - A bigger table saw isn't better!
Cross Cut Guide
Another jig I use a lot, is a cross cut sled. The guide rails are left over oak edging. Put some wax on them.
Cross Cut Sled
If I need a 45 degree cut, I simply clamp a plastic rafter square to the base. Don't ever use a steel square as a cutting guide. I would not like to accidentally cut into a steel square - the result of tungsten saw teeth binding into a steel tool won't be fun at all. This sled has seen heavy use over the past year.
The Simplest Jigsaw Guide Ever
There are many videos on Yootoob showing how to turn a jigsaw with a log flexible blade into something resembling a band saw, using a wooden overhead arm and ball bearings. You don't need any of that.
Simply buy Professional quality blades. It is the same type of blade you always buy, but with a P at the end of the part number. Those blades are thick and stiff. They don't flex and they cut straight!
Jig Saw with Dust Port and Professional Blade
Here is a picture of my little jigsaw, with a professional blade and a conical PVC rubber adaptor for the little 21 mm dust port to fit a vacuum cleaner hose. You can get the conical widgets on Amazon in packs of 2 to 5. Do yourself a favour and buy a bunch of them.