I find it's often easier to "get to business" when there is a background ready and waiting - And when I just feel like "playing" I'll create a few "background" pages in my journal so they're ready to work with.
There are so many ways to create a background, whatever your favourite tools and techniques, but it's so easy to be tempted by the huge array of materials available in the craft shops.
But it really isn't necessary to buy lots of new tools and colours - there are plenty of options available for low cost - these are a few I discovered:
Using watercolour pencils, simply colour the page with different shades, going darker towards the edges, then smudge the colours together with a wet brush.
This technique can give a "parchment" effect - great for an "aged" appearance and a good base for typography work:
If you have more time, building up layers can give beautiful effects like this (see this video for a quick and easy demonstration).
I also used the "squidging on some hand gel" technique to create lighter areas one the layering was complete.
Dabbing and sponging are very quick and easy - using a wet wipe or (as I do) a corner sliced off a washing up sponge - you can use a palette, or just squirt some colours straight onto the page and dab from there...... If you find you need to highlight an area for your design, simply layer a lighter colour over the background where needed.
Scraping colour with a credit card or ruler gives a geometric feel, and toothbrushes are great fun for splattering.
For a different design, use a bit of shaving foam, to create marbling effects without expensive inks and additives....
Adding texture and depth
Once you have some colour, that may be all you need to "base" your work. Or you may wish to build up some interest. Adding another technique, such as splattering on top of watercolour can be interesting. Stamps and stencils are great and create very beautiful effects - but I don't have any, so I improvise:
A net from the top of a box of oranges makes a great stencil, and textured wallpaper samples from the DIY shop work really well for "stamping" - dab on some acrylic, "print" on some scrap paper to remove excess, then "print" on your work, using a rolling pin for even pressure if needed. Then there's my favourite - bubblewrap - works really well, and you can use one piece over and over.
Quick and Easy
Finally - be on the lookout for interesting backgrounds in magazines (advertisements are often good for blocks of colour without text) and packaging - start a squirrel-store of cut-outs and pages and you'll never be short of a background, or a picture just waiting for some text.
I confess I'm no expert, but these are the tricks and techniques I developed, learned from others through Bible Art Journaling UK and picked up from the Pinterest, Youtube and Google.
If there are any techniques here you haven't tried - be brave and give it a go - and share your own budget ideas with the rest of us!