my best bet of advice is this keyword and this keyword alone:-
Marketing!
Marketing can be your best friend when youre small and upcoming
try to build up your portfolio soon as you said that youre doing, and though you may be small on twit and insta thats ok! make sure that youre using hastags to get your work out there, share what art you have now in groups, start talking to more artists and making friends, reply to the posts you see going around that say things like 'share your work here/ tell me about your ocs/ what art pieces are your favorite' and other posts like that
the more you interact with people the more you gain attention
and once you have more attention THEN be sure to advertise that you have a kofi and patreon
people want to be sure that they can support you, that theyre getting something rewarding out of it
thus its really important for you to have that artwork and interaction first, otherwise people wont be interested
now ko-fi's are simple enough ofc
people can just donate if they feel like, or you can offer things to people like ex:-
making a post that says 'Drawing chibis for __ amount of ko-fi's' etc
make sure to follow the official ko-fi account on twitter!
they give away ko-fi's sometimes, or post things to help promote certain accounts
thats all i really have to offer as i havent done anything for my patreon
but you can start out with a $1 tier maybe? offering sketches and wips maybe
whatever your like!