These are in my opinion the most useful and essential tools that you need when using Steemit, although you can use Steemit perfectly well without these, but i'm sure you wont be as successful and understanding of what is going on. Using these tools you have the ability to become more successful. I'm going to do a brief summary and explain the basic elements of each.

Steem World

This is an incredibly useful website to view all your data under a nice easily usable UI. It allows you to see the rewards you will be getting and a nice brake down of how much of each Steem & SBD you will get as well as how much you have used to promote it, and you can compare amount spent vs income in dollars. Also shows your Steem Power and what it is currently and what it is worth when at whatever percent you wish.

Another really useful element is the ability to see how much you will make from curation rewards, there are so much data available and i'm not going to list all of it, but if you ever need any information about your account this is the place.

Steem Connect

This is a simple identity layer built on top of the Steem blockchain, it allows you to connect to authorized apps is a secure and convenient way. This is vital if you want to use 3rd party apps, such as Steem auto which I will mention later in my post. It gives apps authorization in able to do what it needs to do. Its incredibly quick, and hopefully trustworthy as its been linked to Steemit Inc themselves.

Steem Engine

This is one of the more basic apps, it allows you gain more follows and upvotes. You have a limit of following 15 people per 24 hours, the more upvotes the more points you gain and so you should receive that amount in followers. This is very useful for gaining followers when you first start out, and also getting small upvotes from other small accounts. However with the new Bandwidth managing system and use of RC using this app could cause problems, so make sure you watch your RC when using it.

Steemd

This is very similar to Steem world as its basically a collection of information fetched from the Steemit blockchain but is more based around resource credits and the bandwidth you use, as well as all the actions on your account. Its quite useful to measure your resource credits which in my opinion is higher in detail compared to Steem world.

Steem Auto

This is the most useful app for me personally, you can use this to create Curation trails which when followed means you upvote all the posts the leader of the curation trail upvotes. This is very useful to support certain members and also increase your curation rewards through following expertly designed trails. You can also support your friend's post by setting them up in the fanbase as an auto upvote. The settings for all of this are very adjustable and once you get the hang of Steem, I would highly recommend at least understand this service.