Step 1: Materials and First Step
Get your piece of card and work out how big you want the top part of your table, the bigger the piece of card, the bigger you can have your top surface without having tiny sides (legs).
Once you have worked out how big you want your top surface, measure your card's total length and minus the top surface length. Divide the left over amount by four, (this is for your sides/legs).
With this amount, depending on your measurements, make the first cut (inside leg) slightly longer than the outside (2nd) leg, approximately between 1-2cm's depending on what your measurements are.
For example: I had card which was 125cm long, I wanted a top surface of 30cm, which meant my sides were 24.5cm-inside, 1st cut, and 23cm-outside, 2nd leg.
Then measure this out for each end and mark it on your card with the pencil.