( I honestly recommend a character you like but do not see done often, to spice up the variety. If that doesn’t happen to apply, I guess go for the one you feel you know the best?
As for tips, uh, keep in mind this is mostly my opinion and perspective, so it’s not law or anything:
Make sure you know the character you are doing the ask blog for. This includes knowing more about the surrounding culture for the character, and their setting and what it’ll imply. Research is important so you don’t make amateur mistakes, like saying there are janitors in a japanese school (the cleaning is handled by the student body, particularly people in cleaning duty). If you live in the environment of the character, it makes it 99% easier on you to be well aware of the do’s and don’t s of the area, otherwise research will probably help you understand the character more and their surroundings.
Do not push yourself too hard. It’s important to push your limits, but if certain asks make you uncomfortable or leaving the box open for long, do what you feel is best for you. Take your time answering asks, keep the pace comfortable.
You can do asks out of order and it’s okay. Sometimes starting out you feel you owe it for older asks to be done first, but I honestly recommend doing the ones you feel you can do easiest first, then save the rest for more thinking time.
If your character has a condition in particular that you don’t know much about, study it. An example is Conan’s congenital amusia.
Your ask blog does not have to be drawn out. It can be written, voiced, cosplayed, or done with other sorts of media. Feel free to be creative.
You set your own limits. If certain sorts of topics make you uncomfortable, make sure to make a rules page and list out what you do not want to deal with.
Your ask blog doesn’t necessarily have to be canon. Feel free to have a bit of fun with some things. You can also feel free to fill in stuff we don’t know with headcanons, and you can always change something that doesn’t suit your tastes with AU. Make sure to list it, but remember that no one is obligated to like what you change or add. At the same time, it doesn’t give them the right to be rude to you (except on the chance that the change or headcanon is offensive). Mine are personally always as close to canon as I can get, but I know everyone’s taste will vary, so do as you will on your blog, it’s yours.
Be open to critisism. Do not let yourself be stomped on by aggressive and mean people, but respect people who politely inform you about corrections or something you could possibly look into.
Don’t worry about schedules or being on time with anything. This is something you’re doing for fun, none of us are getting paid for this.
Most importantly, enjoy yourself. If you find the ask blog is becoming a drag, feel free to put it on hiatus or quit. It’s not an obligation, it’s something you are doing for fun.
Because Shinichi is everyone. If he’s Ran, Conan and Kaitou Kid, I extend it since he’s Kaitou Kid then he’s Kaitou Kuroba and Toichi Kuroba and Jii-chan. Then Haibara once dressed up as Conan who is Shinichi but actually Haibara is Shinichi too but you know who Haibara is???? Sherry. You know who once was Sherry? Kaitou Kid. Kaitou is made of 6 letters. Kid is made of 3 letters. Three 6s = 666. Shinichi is illuminati confirmed.