The first useful thing is a lexicon. Here are the terms I commonly use in my instructions. I will add to it if a new term appears in a project.
CLIP : We talk about clipping when you cut a seam allowance after having sewn it, either in a V or with a simple little notch to allow the fabric to better position itself. We clip when there is too much or not enough fabric to allow a seam to stay flat. If you forget to clip there will be creases or bumps.
DOLL NEEDLE : A doll or stuffing needle is a long needle that goes through stuffed objects. It is generally larger so it will not bend during work.
EMBROIDERY NEEDLE : An embroidery needle has a slightly larger eye to allow thicker threads to slip through. I often use a #7 embroidery needle.
EMBROIDERY THREAD : A quality thread makes all the difference, both during work and for durability. I prefer the DMC brand, 100% cotton, it's easy to find and offers a superb range of colors.
FABRIC MARKER : There are several different fabric markers and chalks. You have to choose the right one according to the work you do and your preferences. To make tiny objects I recommend a marker that disappears with heat. I really like the brand Frixion.
FABRIC SCISSORS : Indispensable for cutting all pieces of fabric. No need for special scissors, just the ones you use in all your sewing projects.
GRAIN LINE : The grain line is usually the right direction of the fabric. Pattern pieces have an arrow marking it. The arrow on the pattern should be parallel to the selvedge. Cutting the pieces of fabric on the grain line ensures that the doll when sewn will not be crooked.
HEM : This is the edge of a garment like the bottom of a pair of pants.
INTERLINING : It is a "fabric" which is used to solidify another fabric. It is usually white or black, and comes in different thickness and texture. It can be iron-on (which sticks to the fabric with the heat of an iron) or not. The main purpose of interlining is to stabilize the fabric.
NOTCH: A notch is a small mark on the pieces of fabric which allows them to be aligned, a mark when you sew.
PRESS : It means to iron. This greatly facilitates handling and precision.
RIGHT SIDE OF FABRIC : This is the good side, the one where there is a pattern or texture, the one you want to see when the project is finished. Some fabrics are identical on each side. Sometimes the front and back are interesting, it's up to you to choose which one you prefer, and be careful not to make a mistake when sewing.
RIGHT SIDES FACING : This is a way of layering fabrics before sewing. The pieces are often placed right sides together before sewing them together. When flipped, the seam allowance is hidden on the back.
SEAM ALLOWANCE : A seam allowance is the space between the stitching and the edge of the fabric. When you sew, you need to place the fabric under your sewing machine foot so that the needle is the correct distance from the edge. Most sewing machines have markings to help you respect the seam allowance. If you don't respect the seam allowance of your project it may not be the right size, you may also encounter difficulties in making pieces match together. In the Tiny Sewing Club seam allowances are shown on the pattern pieces with as a dotted line.
SELVEDGE : This is often the finished edge of a fabric. It is easily seen in printed cottons as the white edge, sometimes there are even things written on it. On a plain fabric, it is noticeable by its slightly tighter weave, small visible holes and sometimes a thread of another color is inserted.
SEWING NEEDLE : There are a variety of sewing needles to choose from depending on the materials used. Choosing the right needle can transform a job from difficult to pleasant. I usually prefer a very fine needle, although it is more difficult to thread it, the reward is a needle that glides like butter through my fabric. The size of the needle depends on the fabric and the work to be undertaken.
STOPPING POINT : In order for a seam to not come undone, stopping points must be made. On the machine, start sewing 2-3 stitches, then reverse them before starting to sew. Repeat at the end of each seam. By hand, it's a knot.
THREAD CUTTER : A thread cutter or smaller scissors can come in handy when you're at the machine and when embroidering.
WRONG SIDE OF FABRIC : This is the wrong side of the fabric, the one that will be hidden inside once the project is complete.
If you have seen terms that you do not understand and you would like me to explain them here, let me know.