I have decided to cut the grass around the house using a manual push mower which works like a charm, except on the edges. I have a lot of edges like the one in the picture below and I don't really know how to efficiently deal with it to make the grass look nice. I have tried with scissors but it's a lot of work and it doesn't really do a good job. The grass sometimes goes in between the blades and it doesn't cut it properly. Tried with different scissors and there is the same problem. Besides, it doesn't look that good even if I manage to cut it. It's not straight. Does anyone have any experience with this that would like to share with me? What kind of methods/tools are you using to fix this issue? It has to be manual, as I don't want any electric/gas-powered machines. I would appreciate even advice on what kind of tool could do that kind of work. I may be able to build it by myself, but right now I have absolutely no idea and I'm new to this "field of work". Any help/advice is highly appreciated!
I've used a pair of old-fashioned sheep clippers for years, and they work fine (with occasional sharpening). Because there are no moving parts, there's nothing to "catch" or break. When you clip with a good pair of leather gloves they're surprisingly comfortable. There are also tools like this one specifically meant for grass trimming, which may be easier on your hand. I've used these in the past and was not impressed (they're heavier than the clippers mentioned earlier). This same tool has also been adapted so that you can use it while standing, although I'm tall and this would be too short or me.
I presume you mean the grass that grows up against the vertical edge of the raised beds; yes, this can be a challenge since the push mower won't get closer than about 3 inches which leaves room for weeds and grass to grow long. The old fashioned solution would have been a hook and crook which would have waited for the growth to get long enough (a foot or more) which could then be gathered by the crook and cut with the hook or sickle.
Here's a suggestion: if you place a length of full dimension 2x2 wood against the bottom of the raised bed the grass would not be able to grow under it, but you would be able to put one wheel of the push mower up on the 2x2 and carefully run the mower in tilt mode close up against the bed. This would keep the grass at the edge to the 2 inches plus the height the mower reel is set at less a bit because of the angle of attack. It's up to you to assess whether this would leave the grass looking odd or not. Examine the construction of the mower to see if the two inches of width would give enough room for safe operation and effectively cut the grass.
A slight modification of this would be to arrange things so that the 2x2 was easily removable. With the lumber in place the grass and weeds would become etiolated and forced to grow sideways away from the bed into the normal path of the mower; remove the wood and run the mower as usual, then replace the wood.
(My $100 battery electric whizzer does a great job, fast and easy.)
There is a very good method with manual tools that old fashioned professionals like me use that won't stress your back too much, but you need two tools; a half moon shaped lawn edger (sometimes called an edging knife, image here https://www.argos.co.uk/product/7216952) and a pair of long handled lawn edging shears like these https://www.argos.co.uk/product/7216952 - some lawn edging shears have blades that face forwards, you need the ones that go sideways, as illustrated in the link.
In spring, go round all the edges with the half moon edging tool, taking out about half an inch of lawn and soil to a depth of about an inch. When you've cleared away the debris, then go round with the lawn edging shears, pushing them into the gap you've made, to clip and neaten the edge. Cutting out that half inch of lawn means, whenever you cut the grass, you just need to use the lawn edging shears to do the edges.
You will need to use the half moon edging tool every spring - sometimes, if growth is excessive, you may need to repeat that in fall/autumn to keep those edges clear and neat during winter, but mostly you will only need to use the lawn edging shears regularly, and the half moon edger in spring, as lawn growth begins.