Writing about spell fumbles and Read Magic reminded me of another frequent complaint about low-level magic-users in OD&D/AD&D: they don't really get to use much magic. It's not so much that they aren't effective (the "wand of sleep with a single charge" complaint,) since there's more to being effective than just casting spells. But their shtick is being magical, and until they get a magic item, they aren't very magical very often. This is often cited as a reason to switch to spell points instead of using Vancian memorization.
I'm not so sure that letting MUs cast spells more often is necessary. Sure, I've dabbled with the idea, if it's necessary for a specific setting, like this fix I came up with for playing wizards from the "Legend of the Seeker" TV series: roll (spell level + 1) d6s, look for matches: if the total of the matching dice is higher than the character's level, there's an unfortunate side effect. If Zedd's a 13th level wizard, he can use Burning Hands all day without risk.
One solution I've seen proposed that doesn't ditch Vancian magic is to let MUs use minor (cantrip-like) spell effects that match spells they have memorized; that MU with Burning Hands can light his pipe magically. Or let that MU describe otherwise ordinary actions in a magical way: anyone can light a fire, but when the MU with Burning Hands does it, it's obviously magic.
That's fine as far as it goes, but if you want low-level MUs to be effective, you could just use the official solution, or one of the official solutions, anyways: in the Holmes Basic book, magic users can write scrolls for any spells they know and can cast. Cost is 100 gp and 1 week per level. I'd change the cost if the MU gets the ingredients themselves instead of buying them on the open market: 3d6 gp for common ingredients, plus a fresh quill from an extraordinary beast of HD greater than or equal to the spell's level, plus blood or ichor from a similar beast with an ability in some way related to the spell's subject. Figure you can also sell such quills for 30 gp/HD, or one inkwell's worth of blood/ichor for 60 gp/HD; you can buy them for about that price, but could try negotiating for a discount.