Useful quick tips
Separate this into single notes when you have time.
When you select two vertices and hit J key, it will create a segment/edge between those vertices.
If there is vertex connected to an edge and if that edge is the only edge that is connected to the vertex, to remove the edge without removing the vertex, whe you are on the X menu, instead of using disolve edge, which will get rid of the vertex as well, you have to instead select limited disolve.
If you want to select the two edge loops which makes the two sides of a surface loop, you can select the surface loop in face selection mode and then you can go to:
Select > Select Loops > Select Boundary Loop
When you want to bevel something and if you have some weird issues even though the topology is good, then, always check the face orientation, as this can be the reason. Shit+N to recalculate the external faces.
When you select several faces that are not necessary such as inside a circle. Instead of deleting all and recreating new faces, you can just press F and it will create a new clean surface, above them all. So this way you don't need to delete those faces?*
While using Looptools > Space, you can use the edges too instead of vertices. Sometimes it gives better results. I guess that the difference of this compared tothe vertex mode is that it keeps the boundaries of the edges untouched, and it does everything insode of the region.
Add and edge loop next to the fillets to avoid having stretching. Bit still, before doing this, try it, I am not sure if it is necessary on a low poly modelling.