Hi OP. A good IFA will live up to the old adage 2 ears, 1 mouth, and have you, and your goals front and central. They won't use it as an opportunity to boast about their expertise or how wealthy they and their clients are.
They will use this to formulate a plan and keep this under review. Cashflow planning will make up a big part of this, and should be revisited at least annually at your reviews.
Charges-wise, 0.5%-1% for ongoing advice is reasonably standard, but this will cover the ongoing review process and additional fees are only likely to be payable on a new piece of planning, rather than tweaks to the existing plan.
A good IFA will also be unafraid to tell you they can't help you and not take you on as a client. If fees will be uneconomical or unjustifiable etc.
People here seem to be obsessed by investment returns. While this is not to be ignored, you need to be careful comparing apples with pears and use appropriate risk benchmarks. An IFA will have some degree of investment expertise but they are not investment managers and in this day and age are unlikely to construct a portfolio, instead using model portfolio funds and discretionary investment management. Don't compare temporary success of DIY'ers with an investment selected based on your risk tolerance, capacity for loss, timescale and objectives.
Furthermore, missing out on tax allowances such as ISA allowances, pension contribution allowances, CGT annual exemptions, making use of spouses allowances etc. is a huge own goal.
Read reviews, get referrals from friends, stay away from big networks, especially SJP.