I have a couple of friends who stopped tripping after a bad trip. One of them just said he was done--never again. The other one enjoys and wants to keep tripping in the future, but gets really nervous about it and has backed out nearly every time since that it's been offered. The one time he's tried since, on a low dose of a mild hallucinogen coupled with alcohol and a clonazolam, he's gotten severe anxiety on the comeup. It's definitely a situation where his own fear of that he'll get anxiety during the trip makes him very anxious--which of course spirals into a severely anxious trip.
The standard recommendation would probably be to try a very low dose in the future,so that you can navigate the psychedelic headspace at a manageable level. However I'm of the opinion that low dose trips can sometimes put people somewhere in that uncanny valley where things feel "off" but you aren't tripping hard enough to let go and embrace the experience. This seems especially likely to someone who is anxious about tripping. The muscle tension and the feeling of energy, feeling that you can't fully express yourself, the rushing feeling as you come up--all of those sensations that you begin to feel at onset of a psychedelic experience--will of course be triggers for your anxiety, because they preceded and accompanied the uncomfortableness and trip anxiety that you've experienced in the past.
It's also worth noting that LSD in particular might be uncomfortable even at low doses because of it's affinity for dopamine receptors--and perhaps more importantly because of its partial metabolism into 13-ho-lsd, which is even more active at dopaminergic sites. (in fact, many prescription dopamine receptor agonists in use today for Parkinson's, etc. are ergoloids). While I personally find mushrooms more likely to cause a bad trip than LSD, many people feel that the opposite is true. But a low dose of mushrooms is in my opinion likely to cause much less anxiety than a low dose of LSD.
First of all, you should do everything in your power to give yourself a calm set and setting for your trip. Ask close friends to be with you for the come-up and ask them to calm/soothe you, or distract you if necessary. Avoid strangers or people who make you uncomfortable. Trip in a space that you can relax in, that has positive associations. Consider exercising prior to your trip, and stretch before and during the come-up to avoid muscle tension and physical sensations of anxiety. Make sure you get a good night's sleep, and eat a good meal, prior to dosing. Try to eat a light snack--some fruit, or a smoothie, etc.-- at some point during the trip to keep your blood sugar in check. Have lots of things planned to do--preferably things that involve being moving around and staying physically active.
If you haven't tried using benzodiazepine before dosing, you should. If you were able to drink, I'd recommend that you try that first. You could also consider over the counter or herbal anxieties remedies like l-theanine (the chemical that makes green tea calming), hops, lemon balm, etc.
Note: Don't take melatonin. My experience--and a number of other reports, if you care to look--suggests that it tends to intensify trips--increasing vasoconstriction and feelings of confusion, generally resulting in a foggier and more alien experience.
Generally speaking, I suggest that people minimize use of benzodiazepines or other sedative "crutches" because they can take away from the magic of the experience. But it might be helpful in your case as a way to "smooth the path"--enabling you to tread on psychedelic territory again, to teach yourself that you can have a wonderful and anxiety-free psychedelic experience. Maybe just once will be enough to improve your comfortability in the future, or perhaps you'll need something to calm you down in subsequent trips for quite some time.
Hopefully a minimal dose should suffice to take the "edge" off your experience and help you cope. However, if a moderately-dosed benzodiazepine isn't sufficient, than perhaps you should shelve psychedelics for the future--maybe try again a few years down the line, in a different life environment, with an arsenal of new experiences, relationships, and hopefully some personal growth to fill your thoughts and distance you from your old anxieties.
Whatever the result, best of luck to you! Psychedelics are tremendous tools for introspection and positive growth: Though use of psychedelic drugs certainly isn't essential to living a fulfilling life, a positive psychedelic experience--a truly "good trip"--could enrich nearly anyone's life.