Well firstly, I believe voting tactfully isn't how it's supposed to work. So when people say it's a wasted vote then what you're saying is everyone's vote is wasted and there's no democracy because it sure as hell isnt a useful vote if you have to vote for 2 extremely poor parties.
Personally I've always voted ukip but only because I've never had any decent indepedant candidates, who usually I much prefer in terms of policy. Party politics has ruined how parliament should work. Don't get me started on career politics. I know some people will say that ukip is racist but I think that's very narrow minded, I've looked at the manifesto and there isn't anything racist there at all. All I see is sensible policies. Esspecially no party whip with councillors. Oh focusing on road maintenance which is poor at best is another great one.
I personally don't put my self into a set camp (right wing/left wing) I just go with my personal beliefs on each area of discussion. I.e I feel corporation tax is too low and non domicile status is terrible but also immigration is unmanageable at its current rate. Which some would say are opposing ideologies.
I vote ukip because other than the Green Party, the conservatives, labour and liberals have all proven in the past to have done poorly in government. Someone new and untested is required. If there was a representative vote party or take money out of politics so it isn't so corrupt party then I'd vote for those but seeing as those aren't an option it's the greens, ukip or an independent, although independents seem to be very uncommon now.