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.
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 leave it that way. I never cut at an angle with a bench saw - I use a jigsaw for fancy cuts.
When selecting a hand 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 saw is rather wobbly, so I learned from the experience.
I made a 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.
The top overhangs the sides of the box by 5 cm, to enable the use of simple guide blocks and clamps.
The saw guide 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.
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 back at you. A ten inch table saw is a killer - a bigger table saw isn't better!
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.