1 - Any guitar will do.

While I would recommend buying a suitable guitar if you know you're serious about playing, there's nothing wrong with having a go with whatever you have access to. Before I could play, there was an old spanish guitar lying around my house which I'd occasionally pick up and try to play a tune on. The only thing that mattered was if I got the notes right, or at least if I thought I did.

You'll know if you're passionate about your instrument regardless of the quality. There are also countless examples of very successful musicians starting out on very little - for example: Dave Grohl using a pillow and a couple of sticks. Just go for it.

2 - Learn music you love.

Learning can be painful. By it's very nature, you are pushing yourself out of your comfort zone every time you learn. Many people quit learning an instrument in part because the music they learn/play has no link to what they'd choose to listen to. This happens often when music is taught in schools and in groups - after all, what music could possibly please everyone?

When I began learning the guitar, I was really into Guns N' Roses and Foo Fighters. I spent a long time going through their catalogues and trying to find any song of theirs it was possible for me to play. Looking back it was a great approach and it's one of the reasons why I encourage students I teach to incorperate music they love into their learning. Without the pleasure of a song you love accompanying the discomfort of learning a new skill, playing will feel all too much like a chore.

3 - Play shorter, more regular sessions.

Playing more regularly but for less time is a more efficient way to learn in my opinion. Getting your head around playing an instrument as a beginner is demanding mentally and you may find that quickly it becomes hard to concentrate. Additionally, your hands will likely ache after some time trying to stretch into chord positions and play sequences of notes.

These are all good things, it's proof your mind and hands are at work and being pushed to their limits. Nonetheless, they will both stop you from being able to just continue playing as if you've just picked up the instrument. You need to take breaks. Additionally we process memories in our sleep, so it only logically makes sense to be doing something on more days if we want to learn quicker.

4 - Learn songs/tunes you know.

Having a good idea in your head about how something should sound before you play it will make the process of learning go much smoother. You'll instinctively know something's not right in the way you're playing a part, giving you the oppertunity to make some changes. In other words, it'll speed up the whole trial and error process.

5 - Consider getting a teacher.

While the internet is abundant with content these days in terms of learning resources, it's also designed to consume as much of your time as possible. This is the problem with learning for "free". YouTube for example is a great platform for both entertainment and education but it's creators are rewarded for using more of your time, so you can be advertised to.

In contrast, with a teacher you pay upfront for a personal tailored learning experience. A good teacher should guide you towards improvement, understanding your own challenges and goals. It costs money but it's a more time efficient way to learn and if you consider your time to be worth money then it's an investment. This is why in my opinion, if learning your instrument is something you really care about, you should consider it.