Group - important to keep object together. You may need to do this if you are working with patterns that need to be laid out with other elements and you want ot keep the together. If you find that you will be doing extensive work with a group of objects you may want to place them in a separate layer. To access this feature go to the top menu and choose: Object> Group

Layers - work in similar fashion to Photoshop. If they don't show up when opening Illustrator, go to the top menu and choose: Window > Layers.

Type Tool - quite similar to Photoshop, though much easier to adjust text. Play with the tracking and Kerning.
Tracking: overall space between the letters and words.
Kerning: space between two letters
Leading: space between lines of text.
knowing this terms is important. You should experiment with all features in Illustrator.

You can resize type like you resize any other object in Illustrator. Remember that if you want the resizing to be proportionate hold down the shift key and move click and drag the text as you desire.

Create Outlines - Text is not treated line an actual illustrator object. If you find that you want to modify the text like you would other objects created with the pen tool for example, then select the text with the text tool and at the top menu select: Type > Create Outlines. this will turn the text into a modifiable object. Choose any of the tools that you would use to adjust anchor points.

Warp Tool - can be useful to shape an object without using the direct select tool or the Convert Anchor Point Tool. To use it, select it from the menu palette and click and drag into any shape you've created. You may push in or out, depending on whether you start inside or outside of the shape. To adjust the brush dimensions, double click it and make adjustments as desired. Experiment. Also experiment with all the other variations of the warp tool found along with it.

Mesh Tool - Useful to create anchors inside of an object that would otherwise be flat. You can color the nodes with different colors thereby creating a sense of three dimensionality if done properly. Access this tool from the palette menu, then simply click on the area inside of the object you selected. Then select the anchor point that you want to change the color and then choose a color of your choice from the color palette.

Blend Tool - used to combine two objects as a transition from one to the other. To use this tool, first create two objects (these may be complex objects) then select the Blend Tool from the tool palette menu. click one object then click the next one. Note that it matters which object you click first. If you want to adjust this tool, double click it, then adjust the steps; the less steps the more visible the transformation of the shapes.

Scissors Tool - used to cut shapes. To use it, select it from the tool menu palette, then go to the desired shape and click on one side then another. A line will appear connecting the two points where you clicked. Choose the direct select tool and select the area you cut, and drag. It should move away.

Guides - Sometimes you will need to use shapes as guides. To do this, select your objects (make sure you're on outline mode) then select: View > Guides > Make Guides.