This may sound kinda rude, but why do you only use red to sketch?
short story: i like it
long story: it starts from like traditional sketching where red is a really good base colour, like its not very overwhelming to most other colours so you can use it as an initial sketch layer and its very easy to go over with another colour (i usually like a darker red or a blue, depending on what im planning to do with the sketch),, but its also quite striking on its own so if you do like the sketch then you can leave it that way
also when i want to draw clean lines i like to use layout paper and then a regular black pencil, and layout paper is kind of like a more substantial tracing paper, and red is very visible through the layout paper and, unlike if you had had a greyscale sketch under the layout paper, your clean black lines dont get confused with the grey lines underneath
below you can see the initial red sketch with the darker red refinements of the sonny/pete sketch i did yesterday, and also the cleaner lines i did on layout paper afterwards (i wasnt happy with the sketch at this point, so took it into photoshop for another refined layer)
also i have a red sketchbook i started this year, where all the sketches in it are just red, which i decided to do because i wanted to practice filling space, and chose red because i had a nice new red pencil, and love how red looks less scrappy than pencil, and all the sketches come together and flow nicely and the red brings them together as one whole page but doesn’t overwhelm the individual drawing,, i mean DOESNT THAT LOOK COOL????
now, digitally, the choice of red was just initially transferring the technique, like “oh red looks nice on paper, lets do some of that here” but now i really do think that its a good choice,, and to prove my point i edited some of the lil bennys from earlier
black is just a lil plain and bland, yellow is always hard to see and very easily overwhelmed, pink is too loud and overwhelming, blue is probably my second favourite but you cant draw in blue without bringing sadness to the party, and then theres red! soft, good, not overwhelming, easy to get depth of tone, very visible but not dominant, doesn’t evoke any particular emotion so its very versatile (unless of course you use a very harsh red and really try to bring out the anger of the colour and what not), just pure and good and nice
SO PLEASE, people who made it to the end of this long long red nerd out, GO FORTH, TRY RED, HAVE FUN