Not entirely convinced that's a 'bad habit' as such, reet.
Unless you're connected with a stable, it's nigh-on impossible as a punter to know a horses level of fitness, and you basically have to take it on trust. Clearly, FTO records can be taken into account (for the horse in question and the yard generally), but it still means a degree of educated guesswork is involved. The alternative is not to bet in races where one or more are having their first run, but I suspect that's going to wipe out more opportunities, than it does mitigate risk.
Of course, weighing horses on arrival at the track and making this information public, would go a long way to removing at least some of that guesswork......but that's an idea myself and others have been touting on racing-forums for probably 20 years, and it's never gained an iota of traction.
My bad habit is not leaving enough time to analyse a race properly.
This is less of an issue with big ante-post races, or 'main event' races on a weekend.........but I might start a Saturday thinking I'll bet in three races, win a few quid, and then have a crack in some others to play it up, instead of sticking to my original inclination and trousering the profit. Only just starting to look at a 14-runner 0-125 handicap hurdle 5 minutes before the off, isn't particularly wise as an approach.
Losing runs are for ignoring, imo. Keep doing the basics right, and these will always self-correct eventually.