As long as we're on the topic of what can/can't be done with SVG, I want to cover
Inkscape. Inkscape is an SVG full editor. It doesn't create SVG tiny files, only SVG full files, but with careful use of its "XML editor" (Edit > XML editor) inkscape can act as a stepping stone, for copy-pasting attributes for shapes and paths, making SVG tiny image creation easier (You'll mainly want Inkscape for creating paths).
Important attributes:
Some things though:
General:
Don't use the CSS "styles" attribute from Inkscape, SVG tiny doesn't support CSS. You need to reformat them as XML attributes, example: "fill:red;" becomes fill="red".
Also no CSS units in SVG tiny: stroke-width="1px" becomes stroke-width="1"
Inkscape's circle tool is actually a path. To create a real circle element use the XML editor > "new Element" button and type "svg:circle" (use prefix "svg:") and use the same method with ellipse and polygon/polyline.
Settings:
1. Reduce the numeric precision, otherwise Inkscape will overload on huge 8-spaces decimals and there will be rounding bugs, like 1.99999999 instead of 2.
Edit global Inscape preferences >> SVG Output
numeric precision: 3
Minimum exponent: -3
SVG editing:
1. Avoid adding an unwanted "transform" to a new SVG image (thus flinging shapes around and ruining the simple copy-paste we want), try to set the image size first (File > Document properties) before drawing, then open the XML editor (Edit > XML editor), find svg:g Layer1 in the node tree (left side), select, and finally delete the transform attribute.
If you need to change the image size afterwards, put everything into one big group first
1a. (Edit menu > Select All)
1b. (Object menu > Group)
1c. resize image (Document properties)
1d. see above for removing "transform" on Layer1
1e. move group object back into place.
1f. (Object > ungroup)
2. try to use the grid (Document properties) and, from the toolbox, use only
2a. "Draw Bezier curves and straight lines"
and
2b. "Edit paths by nodes" tools.
3. In your path shapes, try to keep the node count down: avoid the "draw free hand" and "calligraphic brush strokes" tools like the plague, though you can always Simplify (Path menu >> Simplify).