Make it clear up front that you would like your legal fee agreement in writing from your lawyer. This will help you avoid the surprise of an unexpectedly high bill. Make sure that all expenses and fees are itemized, so that you'll have a clear understanding of what exactly you are paying for.
A general practitioner is not always your best option. You might have a good lawyer you trust, but do not hesitate to hire a specialized lawyer if you need help with an issue your lawyer has no experience with. Do not hesitate to ask your usual lawyer for a referral.