Always go into things with your eyes wide open and accept that every industry has its charlatans. Why should publishing be exempt? After all writers are dealing with “dreams” – and what do con artists exploit? Check things out, the Society of Authors is very helpful, and if in doubt use Google. If there’s something dodgy about a company, someone somewhere will have Googled about it. If it seems too good to be true, it is.
Always spell check your work with a decent dictionary and don’t rely on the computer. I find the grammar check more useful but still like to check grammar for myself. All faults are my own etc etc! Be professional in your approach to agents and publishers. Your cover letter/synopsis must be word and grammar perfect.
Make your work as good as it can be before submitting it anywhere. But equally don’t use that as an excuse never to send work out. Ultimately submitting work is the way to get the feedback you need. If it’s really good someone somewhere will want that piece. You’re looking to make sure that nobody can read your work and automatically dismiss it. You want them to read it, love it, remember it and publish it!