I have a regular sized Kona mountain bike and I've been trying to at least lift the front properly, for several months. Is it maybe that I weight 105 (only)? What techniques would you recommend for somebody like me? I know bunny hops are usually for BMX, but they're useful for MTB a whole lot, for example this channel gives tips on starting, but for adult sized bodies I would suppose. Thank you.
Wheelies are about legs and technique so if you can reach the pedals and handlebars you can pull a wheelie on a mountain bike.
But bunny hops need weight so that will be an issue for you since it's a matter of using your weight to get the bounce and momentum you need.
Learning to wheelie (lift the front wheel) is fairly simple you get the bike barely rolling, put it in highest gear, and then push down hard on the pedal while pulling up on the handlebars. Keeping it going is a bit more difficult. I taught my 8 year old to wheelie using that technique but on a smaller bike. Be prepared to spin the whole bike upside down a few times when learning. But doing it this way you can't really get hurt since you're not going at any speed.
Safety first! Don't take the picture too seriously, but practising on grass is a good idea for beginners.