The Paths Tool can take some practice in order for you to feel comfortable with using it, but it has a couple of advantages over the selection tools that you draw with. Firstly, you can produce bezier curves, and secondly, you can save paths, meaning that you can return to them at a later stage when working with an image.
In this tutorial I'm just going to give you an introduction to the Paths Tool and get you using the features of it to trace around a letter and replicate it as a path. The letter 'r' in Arial Black is a good example for this as it demonstrates using both straight and curved segments.
1. Add Guides
The first thing to do, before even selecting the Paths Tool, is to add guides to the image that coincide with all the vertical and horizontal outlines of the letter 'r'. This will make it easier to draw perfectly aligned segments of your path.
2. Segment 1
Starting at the top left of the 'r', with the Paths Tool selected, click on the corner point. Remember that you can zoom in to ensure you are clicking exactly where you intend. Now move your cursor to top right corner and click to place a new node, which results in a straight segment between the two.
3. Segment 2
You simply place your cursor at the intersection of the upright and arm of the 'r' and click to add another straight segment.
4. Segment 3
The next segment is curved and so the technique changes. Place your cursor at the top right of the arm of the 'r' and click and hold the mouse button. Now drag the cursor to the right and you will see handles appearing from the node and the segment that you have just added will start to curve. Continue moving the cursor until the curve of the segment matches the curve of the letter and then release the mouse button. You'll note that the curve in the image isn't perfect but it is close enough for this example. To make it more accurate, you could use two segments for this section.
5. Segment 4 (step 1)
The next segment is a straight one so place and click on the next intersection of the outline. If things are going right, it should look very wrong right now as the Paths Tool will place a curved segment where you want a straight one – it automatically attempts to follow curved segments with a sympathetically curved segment.
6. Segment 4 (step 2)
Straightening the segment is very easy. Just click on the previous node and the grab handles will reappear. Now click and hold on the right hand grab handle (see red circle in previous image) and drag it to the left until the segment is a straight line that follows the letter (see red circle in this image).
7. Segment 5
The first thing to do now is click on the last node that you added to select it – this ensures that you are continuing to work on the same path. Now click on the vertical upright at the point where the lower curve of the arm of the 'r' finishes and again, while holding the mouse button down, drag out the grab handles until the new segment curves in a similar way to the letter.
8. Segment 6
For this segment, you just click to place a node at the lower right corner. You'll see that this line looks odd with an unwanted curve in it. To fix this, click on the previous node and click and drag the lower grab handle until you have produced a straight segment that matches the letter 'r'. The red circle in the image shows the position of the grab handle after editing.
9. Segments 7 and 8
These two segments are pretty straightforward, just remember to click on the last node before starting again. For segment seven, click on the lower left corner. For the final segment, hold down the Ctrl button and then click on the very first node that you placed at the top left and this will join the two ends of the path to make a single continuous path.
These are all simple steps that will lead you to the final result of having a path in the shape of a letter 'r'. If at any time the path disappears while you're working, just go to Windows > Dockable Dialogs and select Paths and this will display the Paths dialog. Now right click on the Unnamed path in the dialog and select Paths Tool and the path will become visible again.