Voice acting tips?

Have you tried making your voice more nasal?
I do that for my UTAU... only slightly. Not so much that it sounds ridiculous. xD (However I was going for an anime character-esque voice so you may not want to do this)
Also change your pronunciation slightly. Perhaps pronounce everything with a wider mouth. That changes your voice.

Don't plug your nose though, because then you can't say the N sounds xD

I do a lot of acting for my various UTAUs. The things you can vary are accent, cutesy/manliness, strong/soft, etc. Examples of my own would be:

Mito: Dark-ish accent, varies by bank. Moderately strong and as manly as I can possibly do
Shiranai Bero: Open and airy accent, with a strange gender ambiguous range
Kiku: Low nasally female
Akaru: High, strong, and cutesy. Quite a contrast to her personality.

Once you get the hang of acting and keeping it consistent across that single bank, it'll open up the possibilities and you'll end up as yet another lonely voicebank maker like myself.

You should be able to find some voice acting tutorials on YT or something. Even if it's just a tutorial for talking, you should be able to apply the same concepts to singing. Gender's probably the easiest way to distinguish voicebanks by the same voice actor; I remember finding a few for trans peoples helpful (FtM and MtF might be good search words for finding videos). There's lots of talk of changing the formant of your voice by sort of talking forward or back; The same can be applied to singing.

Personally, I like to find different ways of singing a song I like : D I have 4-5 songs that I like to sing as warmup, so experimenting with the delivery is a natural extension of practising. There's that, and/or: pick out a sort of theme-song for your character. It doesn't have to make sense, as long as you can achieve the tone of voice with it. The nice thing about having a signature song is that you can find the voice again by singing it : D (When I was trying to record an edgier voice, my song was "Anthems for a Seventeen-Year-Old Girl"... and it actually helped : P) So if you need to record over several days, several months then it's good to have a tool like that.

It helps to keep a character in mind too, so if you can draw or dollmaker up what you're aiming for, you might get some results that way. It might not come out like you expect on the other end, but at least it will be different! You might surprise yourself with what kind of voices you can achieve! )*O*)9

Don't do anything that'll damage your voice XD And I'd avoid just changing the note cause that might get complicated if you wanna record multipitch or something later.

But the most important thing is that you're having fun and trying stuff out : O I wish you luck! ^^