As far as staying completely within tax regs and not exploiting tax loopholes:
There isn't much of a way around income tax per se, not without loopholes anyway.
Best start would be to form a limited company as a wrapper for your trading.
Give company secretary role to spouse, family member etc.
That allows director and secretary salaries, obviously take both up to the
lower rate tax threshold first before you have to pay upper rate tax,
in other words, no point one salary being 20k over higher rate tax threshold,
whilst secretary salary is 10k under threshold.
That allows excess profits to be contained within the Ltd. co. thus only paying
corporate tax which as scose said is much lower up to 300k than income tax.
Trouble is you can't use it as income without paying income tax.
Simple, as part of the Ltd. co. invest in stocks for dividends using options to
offset capital loss for instance.
Invest in rental property - rental income can stay within Ltd. co. as well.
That gives you the option of releasing capital by selling property and only paying CGT.
Then there's bonus, pension, expenses and so on...
Some links:
Corporate tax:
HM Revenue & Customs: Introduction to Corporation Tax
HM Revenue & Customs: Corporation Tax rates
HM Revenue & Customs: Marginal Relief for Corporation Tax
Ltd co. info:
Ltd Company Formation: Express Accountancy Ltd - Formation Agents
Making tax efficient use of excess company profits
Cutting Your Corporation Tax Liability Through Expenses - The Tax Guide
Cutting Your Corporation Tax Liability Through Bonuses - The Tax Guide
Essential warning though, assume everything on the internet
to do with tax is bullsh1t until confirmed or not by a tax adviser...