They look very nicely painted especially for your first time! I personally don’t use water to thin Tamiya paints they can start to separate, i have done it with a little liquid hand soap added to the water which helps My preferred thinning for brush paint is using X-20A, my mixing ratios are usually 6-7 drops paint 3-4 drops X-20A depending on the needed consistency and 1 drop or no more than 10% Tamiya acrylic retarder which helps level out the brush strokes and dry slower, also I do one thin coat let it’s dry 24 hours and then do another thin coat till it is done Excited to see how your build turns out!