My homemade cleaning tips come from a variety of sources - from books, blogs and tv series. This one comes from the tv series How clean is your house, in which the Queens of Clean Kim and Aggie tackle the dirtiest houses you have ever seen. Often the inhabitants suffer from asthma and other respiratory problems (probably in part from the dust), so the programme often demonstrates non-toxic cleaning techniques.
This tip for shiny bathtubs with minimum cost comes mostly from Kim and Aggy, with one addition from me.
Put the plug in the plughole of the bath. Cut a lemon in half. Rub over the bathtub (and tiles, sink etc - any enamel surface), making sure to cover it entirely with a layer of juice. You will need to squeeze the lemons as you go. Then leave for about half an hour, to let the acid loosen the dirt. Make a cup of tea or do the washing up or something.
Then come back with one of those sponges with a rough side for scrubbing. (See picture). Dip the sponge in the lemon juice which will have accumulated in the bottom of the bath, squeeze out and dip in salt. (I pour some onto a side plate for this). Ordinary table salt is perfect, it's acting as an abrasive. Then scrub with the salty sponge! You will need to dip the sponge in lemon juice and salt several times, but it will get the tub sparkling and shiny. Once you are satisfied that all the dirt has been dislodged, rinse off with the shower head or a bucket of warm water, wiping as you go.
Keep a squirty bottle filled with 50/50 white vinegar and water, and spray after each use to prevent dirt from building up.
NB make sure the pips don't go down the drain!