Here are your supplies:

Start with the paper and pencil

And draw out your capital letter with a ruler to make the lines straight

Join the lines up

Result

Now on to lower case letters: draw it out

And do the diagonal lines again. If it is on a curve then draw at either end or halfway

Correct it to make it more accurate and maybe add a line inside the letter like I have done

Now onto a shape

Draw out the lines again

And join them round

Now a more geometric shape

Draw out the diagonal lines

Join

And there you have it!!