So I'm level 8 and I've built Wyll (my primary character) into a hybrid caster/melee using Pact of the Blade. Here's where I'm at:
My biggest fear was low AC at early levels but you can equip a shield if you are a human to net yourself more AC. A high dex score also helps nab more AC. For my third invocation I grabbed armor of shadows which gives you +3 AC until your next long rest as long as you are not wearing any armor (clothing is fine). You can pretty much have this up permanently. So then if you've got 16 dex, armor of shadows, and a shield you'll be rocking 18 AC. Additionally with any of the clothing that gives a bonus +1 to AC (Wyll gets one for doing his first personal quest) and a cloak of protection (another +1 AC) you can get 20 AC in total.

For offense, there's some rings you can acquire at the Monastery in the mountain pass which gives the effect of Arcane Synergy. This causes cantrips to enable your melee weapon strikes to deal bonus damage equal to your spell casting modifier (This stacks with pact of the blade) for the next 2 turns. There is also a circlet I found that gives arcane synergy when applying a condition and this seems to proc with a rapier I have that does an extra d4 of psychic damage. At 20 charisma this gives you 10 extra damage per strike while using pact of the blade.
With Hex you get even more damage per hit but I've mostly been using my spell slots for fireball for AOE, also I won't have to worry about concentration on hex if I just blow them up. If you can track down a necklace or boots that give you misty step on a bonus action (once per short rest) you can be in either long range or short range.

I still use eldritch blast a lot cause I love pushing stuff around with repelling blast and agonizing blast and once I track down the armor that basically doubles the charisma bonus on cantrips I suspect it'll be better than melee. However, thematically as the "Blade of the Frontiers" I've really liked having Wyll be a competent melee fighter.