using alternative mastodon web clients
1. First of all, you'll need a Mastodon account. (skip ahead if you already have one).
No matter which instance you choose, you'll be able to view and interact with posts from people from all other instances. The one exception to this is instances that have been blocked by the admin of your instance. Usually these blocked instances are instances populated by nazis, are full of hate speech, or that have harassed other instances or users... you know... those types of ppl......
If you'd like to join an instance free of those types of users, there's a list of cool mastodon instances here.
2. Choose a web client.
At the bottom of this page, I've listed some clients. Feel free to experiment with different web clients! You don't have to settle on just one :3
3. Authorize the client to login to your mastodon account.
Different web clients may ask for different login details. Halcyon, for example, asks for you to enter your username like this (without the quotation marks): "@firstname.lastname@example.org" and then takes you to a screen asking you to authorize Halcyon (or it may ask you to login to Mastodon and then authorize it, but I'm assuming you're already logged in to Mastodon).
Pinafore asks you to enter the name of your instance: "your.instance" and then takes you to login to mastodon to authorize pinafore.
Yay! You can now use Mastodon without struggling with the user interface of the default client :D
web clients I recommend
Halcyon: this client mimics Twitter's layout! I highly recommend this if you want a literal alternative to twitter.
Pinafore.social: this client is the one I typically use. It has multiple color schemes you can choose from in settings, and the layout is simple and easy to use.
Brutaldon: If you're into brutalism or oldweb aesthetics, I definitely recommend this one! It has lots of cool themes in the settings menu. I think my favorite theme is either Minimalist (dark) or FULLBRUTALISM.
There are a lot more out there, and there are mobile apps too, but these are the ones I've tried and enjoyed using.
...For iOS, I recommend using Amaroq btw
Update October/7/2019: Amaroq has been acting weird for me lately, but there are still good free apps out there!